Each type has its own strengths and weaknesses, most of which are logical setups. Fire-type Pokémon are weak against Water-type Pokémon, Ice-type Pokémon are weak against Fire-type Pokémon, Water-type Pokémon are weak against Electric-type Pokémon, etc. These matchups also apply to the types of moves as well: A Fire-type move such as Overheat will be strong against a Grass-type Pokémon such as Oddish. Some types of Pokémon are also immune to a certain type of moves, regardless of its attack power, such as using an offensive Ghost-type move on a Normal-type Pokémon.
Pokémon themselves can have up to two types, making them dual-type Pokémon, but moves can only be one type (with the exception of the move Flying Press which is a Fighting/Flying-type move). Most if not all dual-type Pokémon's types correspond with one another such as a Grass/Poison-type Pokémon such as Bulbasaur, or a Rock/Ground-type Pokémon such as Onix. However, not all dual-type Pokémon's types relate to each other like this. Some Pokémon may be dual-type between two types that don't normally go together such as Water/Electric types (such as Lanturn) or Grass/Water types (such as Ludicolo) or Grass/Flying types (such as Jumpluff), or Fighting/Psychic (such as Medicham and Mega Mewtwo X).
Some dual-type Pokémon lose one of their types and gain a different type upon Evolution such as Scyther (a Bug/Flying type) which evolves into Kleavor (a Bug/Rock type). Some singular type Pokémon will change completely to a different type or types upon evolution, such as Azurill (a Normal/Fairy type) which evolves into Marill (a Water/Fairy type). One Pokémon also completely loses a type upon evolution; Gloom (a Grass/Poison type) evolves into Bellossom (a Grass type). Some Pokémon can also change their type altogether, like Eevee (a Normal type) which can evolve into one of eight different types, or Cubone (a Ground type) which evolves into Marowak (a Fire/Ghost type) in Alola.
Some types have special interactions with battle effects:
Starting from Generation VII, Dark-type Pokémon are immune to moves that gain priority from the Ability Prankster.
Starting in Generation VI, Electric-type Pokémon cannot be Paralyzed.
Starting in Generation III, Fire-type Pokémon cannot be Burned. (In Generation II, they can be burned by Tri Attack).
Flying-type Pokémon are not considered grounded, thus not affected by things such as Grassy Terrain and Spikes. If a Flying-type uses the move Roost, it will lose the Flying typing for the rest of the turn.
Starting in Generation VI, Ghost-type Pokémon are immune to effects that prevent escape, and are guaranteed to flee from a wild battle.
Ice-type Pokémon cannot be Frozen (except in Generation II via Tri Attack, and starting from Generation III from non Ice-type moves), are immune to the move Sheer Cold (starting from Generation VII), and don't take damage from the Hail weather condition (Generation III-VIII)/get a 1.5x boost from the Snow weather condition (Gen IX).
Poison-type Pokémon cannot be Poisoned (with the exception of Twineedle in Generation II only, and the Ability Corrosion from Generation VII onwards), and will remove Toxic Spikes from their side if grounded, when switched in. If a Poison type uses the move Toxic, it won't miss.
Rock-type Pokémon gain a 50% Special Defense increase, and don't take damage from the Sandstorm weather condition.
Steel-type Pokémon cannot be Poisoned and don't take damage from the Sandstorm weather condition.
Type Strength Table[]
Here list of the strengths and weaknesses of each type from Generation VI onwards.
Type Defense
Type Attack
½
×0
½
½
½
×2
×2
×2
½
½
×2
×2
½
½
×2
×2
½
×2
½
½
×0
×2
½
½
×2
½
½
×2
½
½
×2
½
½
½
½
×2
½
×2
×2
×2
½
×2
×2
½
½
½
½
×2
×0
×2
×2
½
×2
½
½
½
½
×0
×2
×2
×2
½
×2
×0
½
×2
×2
½
×2
×2
×2
½
½
×2
×2
½
×0
½
½
×2
½
½
½
×2
½
×2
½
½
×2
×2
½
½
×2
×2
½
×0
×2
×2
½
×2
½
×0
½
×2
×2
½
½
½
½
½
×2
×2
½
×2
½
×2
½
×2
×2
½
Unused Type Combos[]
There are currently 9 unused dual types in Pokémon as of Generation IX:
Due to this, several Pokémon have been retyped to take advantage of the addition of new types. For example, the entire Magnemite line was retyped to Electric/Steel and many Pokémon that were previously Normal or mono-type Pokémon became Fairy type following its introduction.
Coincidentally, all of these types have an immunity, with the Dark, Steel, and Fairy types being immune to the Psychic, Poison, and Dragon types respectively.
The Dark type is currently the only one of the three types introduced after Generation I to not be given to an already introduced Pokémon to retype it.
In Pokémon Masters, there are Unity Moves which can use three types if all Pokémon on the players side of the field have different typings.
The type that has the most Pokémon classified into it is Water.
According to Ken Sugimori, adding new types makes it tricky to maintain the battle balance. However, he also stated if Game Freak can figure out how to add types without disrupting the competitive meta, the staff are eager on creating new types.[1]
The only Pokemon without weaknesses is the Tynamo line because of their Levitate ability which makes them immune to Ground, Electric's only weakness.
In Generation IX, a new type was introduced, being the Stellar type. This typing is not natural for any Pokémon, for it can only be accessed for Terastallized Pokémon. Stellar type moves are super effective against any Terastallized Pokémon.
While not evolutionary relatives, several Pokémon that related to each other also have unique type combinations such as:
??? type · Only exists within Colosseum and XD: Shadow · Only exists within Scarlet and Violet: Stellar
