Post by goldensandslash on Sept 21, 2023 22:48:38 GMT
I recently talked about Gen 2 Mystery Gift on Land of Roads. This inspired me to look into it more closely and explain it in more detail. So... here's everything you ever wanted to know about Mystery Gift in Gen 2 and then some!
The first thing you'll need is two Game Boy Colors. Yes, Game Boy Colors. No other model of Game Boy will work for this. This is because the Game Boy Color added an infrared sensor for wireless communication, and this is what we need to use it.
Now, play Pokémon Gold, Silver, or Crystal, up until you reach Goldenrod City. There is a little girl named Carrie located on the fifth floor of the Department Store. Talk to her to enable Mystery Gift. From then on, any time you start up the game, the menu will have "Mystery Gift" as an option, alongside "New Game", "Continue", and "Options".
If you and a friend each press "Mystery Gift", then you'll both receive an item in your games. What items can be obtained this way? Well...
Common = Berry, PRZCureBerry, Mint Berry, Ice Berry, Burnt Berry, PSNCureBerry, Guard Spec., X Defend, X Attack, Bitter Berry, Dire Hit, X Special, X Accuracy, Eon Mail, Morph Mail, Music Mail
Uncommon = MiracleBerry, Gold Berry, Revive, Great Ball, Super Repel, Max Repel, Elixir, Ether
Rare = Water Stone, Fire Stone, Leaf Stone, Thunderstone, Max Ether, Max Elixir, Max Revive, Scope Lens
Super Rare = HP Up, PP Up
Note that the Eon Mail, Morph Mail, Music Mail, MiracleBerry, and Scope Lens are UNAVAILABLE IN THIS GAME through any other means. The first three are just mail, so it doesn't really matter too much, but the other two are unique held items with actual use. MiracleBerry will cure any status ailment and Scope Lens will raise your Pokémon's critical hit rate.
I should note that MiracleBerry is TECHNICALLY available in the game, as a 2% held item on wild Celebi. But there's no way to find a wild Celebi unless you cheat or hack, so I'm including this as "unavailable through any other means".
Now, these are only half of the items that you can obtain in this manner. The other half are just Decorations, but hey, decorations can be cool. The decorations that you can get are:
Common = Jigglypuff Doll, Poliwag Doll, Diglett Doll, Staryu Doll, Magikarp Doll, Oddish Doll, Gengar Doll, Shellder Doll, Grimer Doll, Voltorb Doll, Clefairy Poster, Jigglypuff Poster, Super NES, Weedle Doll, Geodude Doll, Machop Doll
Uncommon = MagnaPlant, TropicPlant, NES, Nintendo 64, Bulbasaur Doll, Squirtle Doll, Pink Bed, Polkadot Bed
Rare = Red Carpet, Blue Carpet, Yellow Carpet, Green Carpet, JumboPlant, Virtual Boy, Big Onix Doll, Pikachu Poster
Super Rare = Big Lapras Doll, Surf Pikachu Doll
So... how does this feature work? Well, first, the game decides whether to give you a normal item or a decoration. After that, it generates a common to give you. But there is a 10% chance that you get upgraded. If so, it generates an uncommon. But after that, there is a 20% chance that you get upgraded. If so, it generates a rare. After THAT, there is a 20% chance that you get upgraded and it generates a super rare. If, at any point in the process, you fail to receive an upgrade, then it just gives you the generated item. However, note that you can only have 1 of each decoration per save file. So if it generates a decoration that you already have, then it just gives you a normal item of the appropriate rarity instead.
In practice, this means that there is a 90% chance of getting a common, 8% chance of getting an uncommon, 1.6% chance of getting a rare, and 0.4% chance of getting a super rare.
Okay, so... what? You just Mystery Gift over and over again until you get lucky enough to get all of the items? Alas, no.
Each save file can only give certain items to other games. When you Mystery Gift with another save file, it takes that other game's trainer ID and runs it through a complicated formula to decide what item you get. Each save file can only give out 8 of the 16 commons, 4 of the 8 uncommons, 1 of the 8 rares, and 1 of the 2 super rares. This applies to the normal items and the decorations. So once you have received everything possible from one particular save file, you have to reset that cartridge to get a new Trainer ID and play up to Goldenrod City AGAIN, just to be able to get different stuff.
One quick word of caution: you cannot Mystery Gift with two games if they are different languages! If you do, it will corrupt your save data on BOTH games. So uh... yeah, don't do this.
I should also note that you are limited to five Mystery Gifts per day, and you cannot Mystery Gift with the same cartridge more than once per day. However, this can be circumvented by just changing the in-game clock to advance to the next day immediately.
Wait... changing the clock? Yeah... so, if you don't know, that's actually a thing you can do in Gen 2. It's a debug feature that you're not supposed to be able to access, but it was left in, for some reason. On the title screen, for Gold/Silver, you have to input Down+Select+B all at once. In Crystal, not only do you have to input Down+Select+B, but then you have to release Down+B while still holding Select, and then hold Left+Up, and then release Select. Once you've done this, you'll be taken to a menu that asks if you want to reset the clock. If you say yes, then you will be prompted for a password. The password you need is generated based on your player name, your Trainer ID, and your current amount of money that you have. Once you input the password, you can set the day and time to be whatever you want.
But anyways, once you Mystery Gift, you can then get either a normal item or a decoration. If it's a decoration, you automatically obtain it and it goes into your PC at home. But if it's a normal item, it doesn't appear in your bag or your PC, like you may think. Instead, there's a guy behind the counter on the second floor of each Pokémon Center. Talking to him will cause him to give you the item. I'm guessing this was done in case the player's bag was full.
And that's Mystery Gift in the Gen 2 Game Boy Color games. However... we're not done, because there's another Gen 2 game to take a look at: Pokémon Stadium 2.
If you connect to Pokémon Stadium 2 via the Transfer Pak, you can Mystery Gift with Carrie herself. The items and decorations that you receive from Carrie are based on YOUR trainer ID, not hers. However, the formula that it runs your ID number through is different for decorations (not for normal items), so you may find different decorations when Mystery Gifting with Carrie. Though, as before, she can only give out 8 different commons, 4 different uncommons, 1 rare, and 1 super rare. So you cannot get everything on a single save file when Mystery Gifting with Carrie exclusively.
And then there's the exclusive decorations that you can only get from Carrie: the Pikachu Bed, Unown Doll, and Tentacool Doll.
So, there is a 0.6% chance that you get one of these items from Carrie instead of the normal decorations. At first, the only one that you can get is the Tentacool Doll, but after beating Round 1 in Stadium 2, you can get either the Tentacool Doll or the Pikachu Bed (split evenly, so each is a 0.3% chance). At least... that's the intention. But there's a bug in the game's random-number generator so that this will NEVER happen. As such, no one has ever gotten these items without cheating, hacking, or glitching.
What about the Unown Doll?
Well, it pretty much doesn't exist. There's data for it in Stadium 2, but it doesn't appear to be able to be given at all. It was probably event-only and those events simply never happened.
I should also note that there are other decorations for your room in Gen 2 that don't require Mystery Gift to obtain. These fall into three main categories.
The first is the easiest, and ones that you likely obtained even if you never knew it: the Fluffy Bed and the Town Map. To get these decorations, all you have to do is start a new save file, and they're already in your PC in your room.
The second is from the money that your mom embezzles from you after you win battles. She buys various items for you throughout the game.
Once she's been given $900, she will spend $300 on a Super Potion. When she's been given $4000, she will spend $270 on a Repel. When she's been given $7000, she will spend $600 on another Super Potion. Once she's been given $15000, she will spend $3000 on a Moon Stone. When she's been given $19000 she will spend $600 on yet another Super Potion. And when she's been given $40000, she will spend $900 on a Hyper Potion.
However, she also buys decorations. When she's been given $10000, she will spend $1800 on a Charmander Doll. When she's been given $30000, she will spend $4800 on a Clefairy Doll. When she's been given $50000, she will spend $8000 on a Pikachu Doll. And when she's been given $100000, she will spend $22800 on a Big Snorlax Doll.
The third category comes from the original Pokémon Stadium. After successfully winning at Gym Leader Castle in the original Stadium, you are given a special Pokémon that can be transferred to a Gen 1 game. These are Pokémon that are otherwise only available once per save file, and require you to make a choice between different Pokémon: Bulbasaur, Charmander, Squirtle, Hitmonlee, Hitmonchan, Eevee, Omanyte, and Kabuto. This way, you can get multiple without trading.
However, even though these appear to be the same as the Pokémon that you can get in the Gen 1 games on Game Boy, they are distinct. Specifically, they have a different held item from normal when transferred to Gen 2. If they came from Round 1, they'll be holding a Normal Box. If they came from Round 2, they'll be holding a Gorgeous Box.
So what do these boxes do? Well, when used from the item inventory, they will give you a decoration in your room's PC, and then disappear. The Normal Box gives you a Silver Trophy, and the Gorgeous Box gives you a Gold Trophy.
Those are all the decorations that exist. You can decorate your bedroom in Gold, Silver, and Crystal with them. But what's really neat is that if you connect to Stadium 2, you can do so in a full 3D environment and it actually looks kinda cool.
A special easter egg also exists with the NES, Super NES, and Nintendo 64 decorations (sadly not the Virtual Boy). In Stadium 2, if you are in this 3D environment, it'll actually show a screenshot from a NES, Super NES, or Nintendo 64 game on your in-game TV. There's four possibilities. For the NES, you could see Super Mario Bros., Donkey Kong, The Legend of Zelda, or Kirby's Adventure. For the Super NES, you could see Super Mario World, F-Zero, The Legend of Zelda: A Link to the Past, or Kirby Super Star. For the Nintendo 64, you could see Super Mario 64, Wave Race 64, Star Fox 64, or The Legend of Zelda: Ocarina of Time.
Anyways, that's enough about decorations. Let's talk about the other use of Mystery Gift: the Trainer House in Viridian City. When you get here, you can do battle against the team of the last player who you Mystery Gifted with. This lets you easily acquire a ton of Exp. Points or Stat Experience, by simply Mystery Gifting with someone who has a team that gives out a lot of whatever you are looking for, and has no attacking moves. Easy enough to set up.
If you've never used Mystery Gift before, then you'll battle Cal, who uses Meganium (PoisonPowder, Synthesis, Body Slam, Light Screen), Typhlosion (Ember, Quick Attack, Swift, Flame Wheel), and Feraligatr (Bite, Scary Face, Slash, Screech) all at Level 50, with no held items. Once you've used Mystery Gift at least once, Cal will disappear from the game forever.
But what about Carrie? What if she was your last Mystery Gift? Does she have a team? Why, yes. In fact, she has three. Which one you face is random. All Pokémon she uses are at Level 50 and have no held items. Interestingly, she uses the sprite of the male trainer to battle, even in Crystal where a female trainer is an option. As a side note, she has a full team of six, and all are Level 50. That... makes her quite a formidable foe.
Carrie's Teams are as follows:
Meganium (Razor Leaf, PoisonPowder, Body Slam, Reflect)
Stantler (Take Down, Sand-Attack, Hypnosis, Dream Eater)
Xatu (Future Sight, Fly, Night Shade, Confuse Ray)
Scyther (Wing Attack, Slash, Pursuit, Double Team)
Politoed (Hydro Pump, DoubleSlap, Hypnosis, Perish Song)
Marowak (Bonemerang, Thrash, Focus Energy, Growl)
Typhlosion (Flame Wheel, Swift, SmokeScreen, Leer)
Kingler (Crabhammer, ViceGrip, Guillotine, Harden)
Electrode (Thunder, Rollout, Light Screen, Swift)
Scizor (Metal Claw, Slash, Agility, Focus Energy)
Porygon2 (Tri Attack, Conversion 2, Psybeam, Sharpen)
Ledian (Dig, Ice Punch, Swift, Safeguard)
Feraligatr (Water Gun, Slash, Bite, Screech)
Crobat (Wing Attack, Confuse Ray, Bite, Screech)
Heracross (Reversal, Counter, Horn Attack, Endure)
Tangela (Mega Drain, Stun Spore, Slam, Growth)
Nidoqueen (Body Slam, Double Kick, Bite, Tail Whip)
Gligar (Sand-Attack, Slash, Faint Attack, Guillotine)
We're not done talking about Mystery Gift though, because there is one more game that you can connect to, and Mystery Gift with. That game is... the Pokémon Pikachu 2 GS.
I'm sure most of you are now scratching your heads wondering what on Earth the Pokémon Pikachu 2 GS is. Well, the Pokémon Pikachu was a virtual pet toy. Basically an off-brand tamagotchi. Except that the "pet" that you take care of is Pikachu. The Pokémon Pikachu 2 GS is a sequel of sorts. Rather than needing to constantly care for Pikachu, though, the sequel is a lot kinder. You don't HAVE to take care of your Pikachu if you don't want to, and no bad things will happen if you don't. But if you DO take care of it, then you will receive "watts". The amount of watts that can be held on a Pokémon Pikachu 2 GS can go from 000 to 999.
The interesting thing about this is that you can Mystery Gift with a Gen 2 Game Boy Color game, and if you do so, then you get an item in the Gen 2 game, and the watts drop back down to 0. When you do this, though, the item you get is NOT up to random chance, but is instead decided based on the hundreds digit of your watts. This means that the more watts you have, the better items you get. 0 gets you an Eon Mail. 1 gets you a Berry. 2 gets you a Bitter Berry. 3 gets you a Great Ball. 4 gets you a Max Repel. 5 gets you an Ether. 6 gets you a MiracleBerry. 7 gets you a Gold Berry. 8 gets you an Elixir. And 9 gets you a Revive.
However, if you had 999 watts, then you instead receive a Rare Candy, which otherwise CANNOT BE OBTAINED VIA MYSTERY GIFT.
That's basically everything there is to know about Gen 2 Mystery Gift. However, there are still some more things we need to discuss.
For starters, the carpets that you can get for your room. It is worth mentioning that there are unused graphics in the game's data that suggests that two more types of carpet existed at one point in development, but they do not exist in-game and there is no way to obtain them.
The other items that I should discuss are the Bluesky Mail and the Mirage Mail. These items are technically programmed as possible items that you can get via Mystery Gift, but there is no way to obtain them without cheating. The only way to get these legitimately is via a Nintendo event distribution, which only ever occurred on the Japanese versions of the game. There's no way to get them on American or European copies of the game at all.
And I think that just about covers everything.
Except... I'm not satisfied.
Even if you were to do all of this stuff, you'd only have 42 of the 45 decorations, since 3 of them are unobtainable. So... you know what? Let's fix that.
Let's get those last three decorations.
Allow me to introduce you to the Coin Case glitch. It basically lets you do a series of seemingly-random things that lets you write code into the game's data. So let's write some code to mark us as having obtained those last three decorations.
First, obtain the Coin Case from the Goldenrod City underground tunnel.
Next, deposit a bunch of items into your PC, so that your PC item storage looks like this (in this exact order):
(anything)
(anything)
X Accuracy x7
TM26 x1
(anything)
Super Repel x94
Stardust x1
(anything)
Dire Hit x87
Super Repel x55
Ether x3
Poké Ball x94
Berry Juice x1
(anything)
Dire Hit x95
Super Repel x3
Pass x1
(anything)
Potion x46
HM03 x1
X Speed x1
Full Heal x18
Flower Mail x51
TM06 x1
(anything)
TM41 x(any number)
Next, catch a low-level Pokémon with bad DVs. Females are guaranteed to have lower Attack DVs than males, but that doesn't help you with the rest of the DVs, so this is pretty random. Put this Pokémon in the third slot of your party.
Then, catch a Quagsire, and teach it Sleep Talk, putting that move into its first move slot. Give it a Protein to hold. Then put it in the fourth slot of your party.
Go to Bill's PC and change the name of Box 9 to be "&♂AL(spacebar)A" (without the quotes).
Save your game while standing right in front of the entrance to the Cherrygrove City Poké Mart.
Reset the game, and load your save again.
Enter the mart, and then immediately exit again. Then walk exactly four steps to the right.
Open your Pokédex and listen to the cry of either Bellsprout, Machop, Machoke, or Omanyte.
Open your bag. If your bag is in the "Key Items" section, move to another section first. Then... from another section, move to the "Key Items" section and use the Coin Case, which just displays how many Game Corner coins you have.
At this point, your game might freeze or reset. If either occurs, then that means the DVs of the low-level Pokémon you were using are too high, and you'll have to try again. Otherwise, you will have successfully obtained the Pikachu Bed. To get the Tentacool Doll and Unown Doll, you just do this exact same thing, except that the name of Box 9 should be "&♂AQ(spacebar)A".
And now you have all 45 decorations.
It's such a huge pain. But guess what? Gen 3 is even worse...
I might make a follow-up talking about Gen 3 at some point.
The first thing you'll need is two Game Boy Colors. Yes, Game Boy Colors. No other model of Game Boy will work for this. This is because the Game Boy Color added an infrared sensor for wireless communication, and this is what we need to use it.
Now, play Pokémon Gold, Silver, or Crystal, up until you reach Goldenrod City. There is a little girl named Carrie located on the fifth floor of the Department Store. Talk to her to enable Mystery Gift. From then on, any time you start up the game, the menu will have "Mystery Gift" as an option, alongside "New Game", "Continue", and "Options".
If you and a friend each press "Mystery Gift", then you'll both receive an item in your games. What items can be obtained this way? Well...
Common = Berry, PRZCureBerry, Mint Berry, Ice Berry, Burnt Berry, PSNCureBerry, Guard Spec., X Defend, X Attack, Bitter Berry, Dire Hit, X Special, X Accuracy, Eon Mail, Morph Mail, Music Mail
Uncommon = MiracleBerry, Gold Berry, Revive, Great Ball, Super Repel, Max Repel, Elixir, Ether
Rare = Water Stone, Fire Stone, Leaf Stone, Thunderstone, Max Ether, Max Elixir, Max Revive, Scope Lens
Super Rare = HP Up, PP Up
Note that the Eon Mail, Morph Mail, Music Mail, MiracleBerry, and Scope Lens are UNAVAILABLE IN THIS GAME through any other means. The first three are just mail, so it doesn't really matter too much, but the other two are unique held items with actual use. MiracleBerry will cure any status ailment and Scope Lens will raise your Pokémon's critical hit rate.
I should note that MiracleBerry is TECHNICALLY available in the game, as a 2% held item on wild Celebi. But there's no way to find a wild Celebi unless you cheat or hack, so I'm including this as "unavailable through any other means".
Now, these are only half of the items that you can obtain in this manner. The other half are just Decorations, but hey, decorations can be cool. The decorations that you can get are:
Common = Jigglypuff Doll, Poliwag Doll, Diglett Doll, Staryu Doll, Magikarp Doll, Oddish Doll, Gengar Doll, Shellder Doll, Grimer Doll, Voltorb Doll, Clefairy Poster, Jigglypuff Poster, Super NES, Weedle Doll, Geodude Doll, Machop Doll
Uncommon = MagnaPlant, TropicPlant, NES, Nintendo 64, Bulbasaur Doll, Squirtle Doll, Pink Bed, Polkadot Bed
Rare = Red Carpet, Blue Carpet, Yellow Carpet, Green Carpet, JumboPlant, Virtual Boy, Big Onix Doll, Pikachu Poster
Super Rare = Big Lapras Doll, Surf Pikachu Doll
So... how does this feature work? Well, first, the game decides whether to give you a normal item or a decoration. After that, it generates a common to give you. But there is a 10% chance that you get upgraded. If so, it generates an uncommon. But after that, there is a 20% chance that you get upgraded. If so, it generates a rare. After THAT, there is a 20% chance that you get upgraded and it generates a super rare. If, at any point in the process, you fail to receive an upgrade, then it just gives you the generated item. However, note that you can only have 1 of each decoration per save file. So if it generates a decoration that you already have, then it just gives you a normal item of the appropriate rarity instead.
In practice, this means that there is a 90% chance of getting a common, 8% chance of getting an uncommon, 1.6% chance of getting a rare, and 0.4% chance of getting a super rare.
Okay, so... what? You just Mystery Gift over and over again until you get lucky enough to get all of the items? Alas, no.
Each save file can only give certain items to other games. When you Mystery Gift with another save file, it takes that other game's trainer ID and runs it through a complicated formula to decide what item you get. Each save file can only give out 8 of the 16 commons, 4 of the 8 uncommons, 1 of the 8 rares, and 1 of the 2 super rares. This applies to the normal items and the decorations. So once you have received everything possible from one particular save file, you have to reset that cartridge to get a new Trainer ID and play up to Goldenrod City AGAIN, just to be able to get different stuff.
One quick word of caution: you cannot Mystery Gift with two games if they are different languages! If you do, it will corrupt your save data on BOTH games. So uh... yeah, don't do this.
I should also note that you are limited to five Mystery Gifts per day, and you cannot Mystery Gift with the same cartridge more than once per day. However, this can be circumvented by just changing the in-game clock to advance to the next day immediately.
Wait... changing the clock? Yeah... so, if you don't know, that's actually a thing you can do in Gen 2. It's a debug feature that you're not supposed to be able to access, but it was left in, for some reason. On the title screen, for Gold/Silver, you have to input Down+Select+B all at once. In Crystal, not only do you have to input Down+Select+B, but then you have to release Down+B while still holding Select, and then hold Left+Up, and then release Select. Once you've done this, you'll be taken to a menu that asks if you want to reset the clock. If you say yes, then you will be prompted for a password. The password you need is generated based on your player name, your Trainer ID, and your current amount of money that you have. Once you input the password, you can set the day and time to be whatever you want.
But anyways, once you Mystery Gift, you can then get either a normal item or a decoration. If it's a decoration, you automatically obtain it and it goes into your PC at home. But if it's a normal item, it doesn't appear in your bag or your PC, like you may think. Instead, there's a guy behind the counter on the second floor of each Pokémon Center. Talking to him will cause him to give you the item. I'm guessing this was done in case the player's bag was full.
And that's Mystery Gift in the Gen 2 Game Boy Color games. However... we're not done, because there's another Gen 2 game to take a look at: Pokémon Stadium 2.
If you connect to Pokémon Stadium 2 via the Transfer Pak, you can Mystery Gift with Carrie herself. The items and decorations that you receive from Carrie are based on YOUR trainer ID, not hers. However, the formula that it runs your ID number through is different for decorations (not for normal items), so you may find different decorations when Mystery Gifting with Carrie. Though, as before, she can only give out 8 different commons, 4 different uncommons, 1 rare, and 1 super rare. So you cannot get everything on a single save file when Mystery Gifting with Carrie exclusively.
And then there's the exclusive decorations that you can only get from Carrie: the Pikachu Bed, Unown Doll, and Tentacool Doll.
So, there is a 0.6% chance that you get one of these items from Carrie instead of the normal decorations. At first, the only one that you can get is the Tentacool Doll, but after beating Round 1 in Stadium 2, you can get either the Tentacool Doll or the Pikachu Bed (split evenly, so each is a 0.3% chance). At least... that's the intention. But there's a bug in the game's random-number generator so that this will NEVER happen. As such, no one has ever gotten these items without cheating, hacking, or glitching.
What about the Unown Doll?
Well, it pretty much doesn't exist. There's data for it in Stadium 2, but it doesn't appear to be able to be given at all. It was probably event-only and those events simply never happened.
I should also note that there are other decorations for your room in Gen 2 that don't require Mystery Gift to obtain. These fall into three main categories.
The first is the easiest, and ones that you likely obtained even if you never knew it: the Fluffy Bed and the Town Map. To get these decorations, all you have to do is start a new save file, and they're already in your PC in your room.
The second is from the money that your mom embezzles from you after you win battles. She buys various items for you throughout the game.
Once she's been given $900, she will spend $300 on a Super Potion. When she's been given $4000, she will spend $270 on a Repel. When she's been given $7000, she will spend $600 on another Super Potion. Once she's been given $15000, she will spend $3000 on a Moon Stone. When she's been given $19000 she will spend $600 on yet another Super Potion. And when she's been given $40000, she will spend $900 on a Hyper Potion.
However, she also buys decorations. When she's been given $10000, she will spend $1800 on a Charmander Doll. When she's been given $30000, she will spend $4800 on a Clefairy Doll. When she's been given $50000, she will spend $8000 on a Pikachu Doll. And when she's been given $100000, she will spend $22800 on a Big Snorlax Doll.
The third category comes from the original Pokémon Stadium. After successfully winning at Gym Leader Castle in the original Stadium, you are given a special Pokémon that can be transferred to a Gen 1 game. These are Pokémon that are otherwise only available once per save file, and require you to make a choice between different Pokémon: Bulbasaur, Charmander, Squirtle, Hitmonlee, Hitmonchan, Eevee, Omanyte, and Kabuto. This way, you can get multiple without trading.
However, even though these appear to be the same as the Pokémon that you can get in the Gen 1 games on Game Boy, they are distinct. Specifically, they have a different held item from normal when transferred to Gen 2. If they came from Round 1, they'll be holding a Normal Box. If they came from Round 2, they'll be holding a Gorgeous Box.
So what do these boxes do? Well, when used from the item inventory, they will give you a decoration in your room's PC, and then disappear. The Normal Box gives you a Silver Trophy, and the Gorgeous Box gives you a Gold Trophy.
Those are all the decorations that exist. You can decorate your bedroom in Gold, Silver, and Crystal with them. But what's really neat is that if you connect to Stadium 2, you can do so in a full 3D environment and it actually looks kinda cool.
A special easter egg also exists with the NES, Super NES, and Nintendo 64 decorations (sadly not the Virtual Boy). In Stadium 2, if you are in this 3D environment, it'll actually show a screenshot from a NES, Super NES, or Nintendo 64 game on your in-game TV. There's four possibilities. For the NES, you could see Super Mario Bros., Donkey Kong, The Legend of Zelda, or Kirby's Adventure. For the Super NES, you could see Super Mario World, F-Zero, The Legend of Zelda: A Link to the Past, or Kirby Super Star. For the Nintendo 64, you could see Super Mario 64, Wave Race 64, Star Fox 64, or The Legend of Zelda: Ocarina of Time.
Anyways, that's enough about decorations. Let's talk about the other use of Mystery Gift: the Trainer House in Viridian City. When you get here, you can do battle against the team of the last player who you Mystery Gifted with. This lets you easily acquire a ton of Exp. Points or Stat Experience, by simply Mystery Gifting with someone who has a team that gives out a lot of whatever you are looking for, and has no attacking moves. Easy enough to set up.
If you've never used Mystery Gift before, then you'll battle Cal, who uses Meganium (PoisonPowder, Synthesis, Body Slam, Light Screen), Typhlosion (Ember, Quick Attack, Swift, Flame Wheel), and Feraligatr (Bite, Scary Face, Slash, Screech) all at Level 50, with no held items. Once you've used Mystery Gift at least once, Cal will disappear from the game forever.
But what about Carrie? What if she was your last Mystery Gift? Does she have a team? Why, yes. In fact, she has three. Which one you face is random. All Pokémon she uses are at Level 50 and have no held items. Interestingly, she uses the sprite of the male trainer to battle, even in Crystal where a female trainer is an option. As a side note, she has a full team of six, and all are Level 50. That... makes her quite a formidable foe.
Carrie's Teams are as follows:
Meganium (Razor Leaf, PoisonPowder, Body Slam, Reflect)
Stantler (Take Down, Sand-Attack, Hypnosis, Dream Eater)
Xatu (Future Sight, Fly, Night Shade, Confuse Ray)
Scyther (Wing Attack, Slash, Pursuit, Double Team)
Politoed (Hydro Pump, DoubleSlap, Hypnosis, Perish Song)
Marowak (Bonemerang, Thrash, Focus Energy, Growl)
Typhlosion (Flame Wheel, Swift, SmokeScreen, Leer)
Kingler (Crabhammer, ViceGrip, Guillotine, Harden)
Electrode (Thunder, Rollout, Light Screen, Swift)
Scizor (Metal Claw, Slash, Agility, Focus Energy)
Porygon2 (Tri Attack, Conversion 2, Psybeam, Sharpen)
Ledian (Dig, Ice Punch, Swift, Safeguard)
Feraligatr (Water Gun, Slash, Bite, Screech)
Crobat (Wing Attack, Confuse Ray, Bite, Screech)
Heracross (Reversal, Counter, Horn Attack, Endure)
Tangela (Mega Drain, Stun Spore, Slam, Growth)
Nidoqueen (Body Slam, Double Kick, Bite, Tail Whip)
Gligar (Sand-Attack, Slash, Faint Attack, Guillotine)
We're not done talking about Mystery Gift though, because there is one more game that you can connect to, and Mystery Gift with. That game is... the Pokémon Pikachu 2 GS.
I'm sure most of you are now scratching your heads wondering what on Earth the Pokémon Pikachu 2 GS is. Well, the Pokémon Pikachu was a virtual pet toy. Basically an off-brand tamagotchi. Except that the "pet" that you take care of is Pikachu. The Pokémon Pikachu 2 GS is a sequel of sorts. Rather than needing to constantly care for Pikachu, though, the sequel is a lot kinder. You don't HAVE to take care of your Pikachu if you don't want to, and no bad things will happen if you don't. But if you DO take care of it, then you will receive "watts". The amount of watts that can be held on a Pokémon Pikachu 2 GS can go from 000 to 999.
The interesting thing about this is that you can Mystery Gift with a Gen 2 Game Boy Color game, and if you do so, then you get an item in the Gen 2 game, and the watts drop back down to 0. When you do this, though, the item you get is NOT up to random chance, but is instead decided based on the hundreds digit of your watts. This means that the more watts you have, the better items you get. 0 gets you an Eon Mail. 1 gets you a Berry. 2 gets you a Bitter Berry. 3 gets you a Great Ball. 4 gets you a Max Repel. 5 gets you an Ether. 6 gets you a MiracleBerry. 7 gets you a Gold Berry. 8 gets you an Elixir. And 9 gets you a Revive.
However, if you had 999 watts, then you instead receive a Rare Candy, which otherwise CANNOT BE OBTAINED VIA MYSTERY GIFT.
That's basically everything there is to know about Gen 2 Mystery Gift. However, there are still some more things we need to discuss.
For starters, the carpets that you can get for your room. It is worth mentioning that there are unused graphics in the game's data that suggests that two more types of carpet existed at one point in development, but they do not exist in-game and there is no way to obtain them.
The other items that I should discuss are the Bluesky Mail and the Mirage Mail. These items are technically programmed as possible items that you can get via Mystery Gift, but there is no way to obtain them without cheating. The only way to get these legitimately is via a Nintendo event distribution, which only ever occurred on the Japanese versions of the game. There's no way to get them on American or European copies of the game at all.
And I think that just about covers everything.
Except... I'm not satisfied.
Even if you were to do all of this stuff, you'd only have 42 of the 45 decorations, since 3 of them are unobtainable. So... you know what? Let's fix that.
Let's get those last three decorations.
Allow me to introduce you to the Coin Case glitch. It basically lets you do a series of seemingly-random things that lets you write code into the game's data. So let's write some code to mark us as having obtained those last three decorations.
First, obtain the Coin Case from the Goldenrod City underground tunnel.
Next, deposit a bunch of items into your PC, so that your PC item storage looks like this (in this exact order):
(anything)
(anything)
X Accuracy x7
TM26 x1
(anything)
Super Repel x94
Stardust x1
(anything)
Dire Hit x87
Super Repel x55
Ether x3
Poké Ball x94
Berry Juice x1
(anything)
Dire Hit x95
Super Repel x3
Pass x1
(anything)
Potion x46
HM03 x1
X Speed x1
Full Heal x18
Flower Mail x51
TM06 x1
(anything)
TM41 x(any number)
Next, catch a low-level Pokémon with bad DVs. Females are guaranteed to have lower Attack DVs than males, but that doesn't help you with the rest of the DVs, so this is pretty random. Put this Pokémon in the third slot of your party.
Then, catch a Quagsire, and teach it Sleep Talk, putting that move into its first move slot. Give it a Protein to hold. Then put it in the fourth slot of your party.
Go to Bill's PC and change the name of Box 9 to be "&♂AL(spacebar)A" (without the quotes).
Save your game while standing right in front of the entrance to the Cherrygrove City Poké Mart.
Reset the game, and load your save again.
Enter the mart, and then immediately exit again. Then walk exactly four steps to the right.
Open your Pokédex and listen to the cry of either Bellsprout, Machop, Machoke, or Omanyte.
Open your bag. If your bag is in the "Key Items" section, move to another section first. Then... from another section, move to the "Key Items" section and use the Coin Case, which just displays how many Game Corner coins you have.
At this point, your game might freeze or reset. If either occurs, then that means the DVs of the low-level Pokémon you were using are too high, and you'll have to try again. Otherwise, you will have successfully obtained the Pikachu Bed. To get the Tentacool Doll and Unown Doll, you just do this exact same thing, except that the name of Box 9 should be "&♂AQ(spacebar)A".
And now you have all 45 decorations.
It's such a huge pain. But guess what? Gen 3 is even worse...
I might make a follow-up talking about Gen 3 at some point.