The Unwritten Rules of the Pokémon Type Chart

We've all seen this image before. It explains each type's strengths and weaknesses. Once you memorize this, you're good to go as far as types are concerned, right? Alas, no.

Because this type chart is incomplete. It gives general data, but several types also have special properties that are not written anywhere and you just have to know.

As time has gone on, more and more of these rules have been added, so it has now become quite complex. This will be my attempt to gather these all in one spot so that I can refer back to it as needed.

First of all, there are seven types that have no special properties at all: Normal, Water, Fighting, Psychic, Bug, Dragon, and Fairy. For these types, this type chart provides all the information you need about them. The others, though, Fire, Grass, Electric, Ice, Poison, Ground, Flying, Rock, Ghost, Dark, and Steel...  we need to take a closer look at.

First up, Fire. A Fire-type Pokémon will have the special property of being immune to burns. No matter how many times you try to burn a Fire-type, you will never succeed. There is, however, an exception. In Gen 1 and Gen 2, this only worked if the move that is trying to burn the Pokémon was a Fire-type move. So, for example, the move Tri Attack, a Normal-type move, would be able to burn a Fire-type in Gen 2. However, starting in Gen 3, this is no longer the case, and a Fire-type cannot be burned at all. The other unique property that Fire-types have is that a Fire-type move, when used on a frozen Pokémon, will unfreeze it. However, there is, once again, an exception. The move Fire Spin will not cause a Pokémon to become unfrozen in Gen 1 or Gen 2. Starting with Gen 3, however, it will unfreeze it.

Next, Grass. Grass-type Pokémon have the special property of being immune to Leech Seed. Ordinarily, status moves ignore the type chart (so, like, for example, you can use Growl on a Ghost), so there's no way to be immune to a status move, but Grass-types are immune to Leech Seed. Additionally, starting in Gen 6, Grass-types gained another property: immunity to powder and spore moves. This is the same immunity that it would have if it had Overcoat as an ability or was holding Safety Goggles. On a Grass-type, the Safety Goggles item is redundant, as it would already have immunity to these moves. The affected moves are: Cotton Spore, Magic Powder, Poison Powder, Powder, Rage Powder, Sleep Powder, Spore, and Stun Spore. Additionally, the Effect Spore ability, while not a "powder and spore move" on the grounds of it not being a move, also cannot affect Pokémon with Overcoat or holding Safety Goggles. Grass-types have this immunity as well, so they will never be affected by Effect Spore. Again, though, this is only from Gen 6 onwards.

Next, we have Electric. Electric-types have the special property of being immune to paralysis, but only from Gen 6 onwards. Not much else to say about that one. Next!

Ice is up next. An Ice-type has three special properties. First of all, it cannot be frozen. There is, however, an exception. In Gen 1 and Gen 2, an Ice-type can be frozen if it is frozen by a non-Ice move (again, I'll cite Tri Attack as an example of this). Starting in Gen 3, though, an Ice-type cannot be frozen at all. The second special property is that Ice-types are immune to damage from hail. And the third is that, starting in Gen 7, they are immune to the move Sheer Cold. Sheer Cold is often cited as the best OHKO move, because the others are either Ground or Normal, and thus, there existed a type (Flying and Ghost) that was immune to them. Sheer Cold, however, had no such type. It would OHKO anything, provided that it hit. But starting in Gen 7, that is not the case, and it would fail to kill an Ice-type.

After that is Poison. A Poison-type, for the most part, cannot be poisoned. I say "for the most part", because the ability Corrosion exists. If a Pokémon has the Corrosion ability, then it CAN poison a Poison-type, overriding this special property. Additionally, in Gen 2, a Poison-type CAN be poisoned by a non-Poison move, such as Twineedle. This is exclusive to Gen 2 and is not found in any other generation before or after. In all other generations, Poison-types properly cannot be poisoned at all, except through the Corrosion ability. Next, let's talk about Toxic Spikes. If a Poison-type is grounded, then when it switches in onto the Toxic Spikes entry hazard, the Toxic Spikes will be removed. As a reminder, a Pokémon is considered to be "grounded" by default. It is, however, ungrounded, if it is either a Flying-type, has Levitate, is holding an Air Balloon, or is under the effects of Magnet Rise or Telekinesis. However, an ungrounded Pokémon becomes grounded anyways if it is under the effects of Gravity, Ingrain, Smack Down, Thousand Arrows, or is holding an Iron Ball. Finally, Poison-types do have one more special property: starting in Gen 6, a Poison-type Pokémon can never miss with Toxic. The move Toxic normally has 90% accuracy (or 85% in Gen 1-4), but if it's used by a Poison-type, the accuracy check is skipped entirely and the move will always hit. This is only the case in Gen 6 and onwards though.

The next type to take a look at is Ground. A Ground-type has two special properties. First of all, they are immune to Thunder Wave, despite it being a status move. Secondly, they will not take damage during a sandstorm.

Flying is up next. A Flying-type Pokémon counts as an "ungrounded" Pokémon. This is notable because several moves (Spikes, Toxic Spikes, Sticky Web, and Rototiller) only affect grounded Pokémon, terrain only affects grounded Pokémon, and the ability Arena Trap only affects grounded Pokémon. A Flying-type Pokémon will be immune to all of that unless it becomes grounded. Additionally, as previously mentioned, a Poison-type that's grounded will remove Toxic Spikes upon switching in. This means that a Poison/Flying will not, unless it is somehow grounded first.

After that is Rock. A Rock-type does not take damage in a sandstorm. Additionally, starting with Gen 4, a Rock-type's Special Defense will be multiplied by 1.5x during a sandstorm.

Next up is Ghost. A Ghost-type has special properties starting in Gen 6. Specifically, a Ghost-type can ALWAYS switch out or flee from a random encounter, regardless of any trapping moves or abilities that may be in effect. Additionally, when fleeing from a random encounter using a Ghost-type, you will ALWAYS get away safely. The attempt will never fail. This is only in Gen 6 onwards, however.

After that, we have Dark. To talk about this, we need to talk about the ability Prankster. This ability, introduced in Gen 5, gives +1 priority to all of your status moves. Starting in Gen 7, though, Dark-types are immune to moves that get their priority increased this way. So if you have a Pokémon with Prankster, don't rely on its ability against a Dark-type, because it won't work. Unless you're playing a game prior to Gen 7.

Lastly, we have Steel. A Steel-type does not take any damage from a sandstorm. Also, a Steel-type cannot be poisoned. However, much like a Poison-type, a Steel-type CAN be poisoned if the Pokémon that is attempting to poison it has the Corrosion ability. Additionally, much like a Poison-type, a Steel-type can be poisoned in Gen 2 by a non-Poison move, such as Twineedle. But, again, only in Gen 2.