Type change

Type change is a mechanic available in Pokémon battles.

In the core series games

Some moves and Abilities cause a Pokémon's types to be temporarily changed, added, or removed in battle. The original types are still displayed in the Pokémon's summary. All type changes are undone when the Pokémon is switched out, faints, or the battle ends.

Through type change, a Pokémon can have up to three types at once or no type at all:

If a new type is added (such as Grass via Forest's Curse or Ghost via Trick-or-Treat) to a dual-type Pokémon, it will have three types at once. However, if Forest's Curse is used on a Pokémon affected by Trick-or-Treat or vice-versa, the new type will replace the previously added one.
If one or more types are removed through Burn Up or Double Shock, and the Pokémon has no more types left, it will become typeless until it is switched out, faints, or the battle ends.

The type change can add or remove type-related immunities to status conditions, such that a Pokémon cannot be poisoned after gaining the Poison-type or Steel-type; or conversely, an originally Poison-type or Steel-type Pokémon can become poisoned after its type has changed (and will remain poisoned even after the battle ends). However, any status conditions the Pokémon already has are not influenced by the type change; for example, a poisoned Pokémon will retain this status condition even after becoming a Poison or Steel type.

If a Pokémon copies the types of another (by using Conversion in Generation I only, Reflect Type, Transform, or via Imposter), the target's type changes are copied as well. If the target is currently typeless, the user will become a pure Normal type. However, if the target was typeless and then gained a type via Forest's Curse or Trick-or-Treat, the user will have two types: Normal and the added one.

The type changes are not transferred via Baton Pass.

Causes

Moves

See also: Category:Moves that change a Pokémon's type

Move	Type	Category	Power	Accuracy	Generation	Notes
Burn Up	Fire	Special	130	100%	VII	The user loses its Fire type after using the move
Camouflage	Normal	Status	—	—%	III	The user has its type changed depending on the environment
Conversion	Normal	Status	—	—%	I	The user's type is changed into the target's type(s)^I or the same type as one of its moves^II+
Conversion 2	Normal	Status	—	—%	II	The user's type is changed into any type that either resists or is immune to the type of the last move it was damaged by
Double Shock	Electric	Physical	120	100%	IX	The user loses its Electric type after using the move
Forest's Curse	Grass	Status	—	100%	VI	The target gains the Grass type
Magic Powder	Psychic	Status	—	100%	VIII	The target becomes a pure Psychic type
Reflect Type	Normal	Status	—	—%	V	The user's type is changed into the target's type(s)
Relic Song	Normal	Special	75	100%	V	If Meloetta successfully uses this move, it changes between Aria Forme (Normal/Psychic) and Pirouette Forme (Normal/Fighting)
Roost	Flying	Status	—	—%	IV	The user loses its Flying type until the end of the turn
Soak	Water	Status	—	100%	V	The target becomes a pure Water type
Transform	Normal	Status	—	—%	I	The user transforms into the target, copying its appearance, types, stats, and moves
Trick-or-Treat	Ghost	Status	—	100%	VI	The target gains the Ghost type

Abilities

See also: Category:Abilities that change a Pokémon's type

Ability	Generation	Effect
Color Change	III	A Kecleon with Color Change has its type changed to the type of the last move it was damaged by
Forecast	III	Castform changes its form and type depending on the weather
Imposter	V	A Ditto with Imposter transforms into its opponent, copying its appearance, types, stats, and moves
Libero	VIII	A Pokémon with Libero has its type changed to the type of the move it is about to use This only works once each time the Pokémon enters battle^IX
Mimicry	VIII	Galarian Stunfisk has its type changed depending on the terrain (for instance, it will become a pure Electric type in Electric Terrain)
Multitype	IV	Arceus changes its form and type depending on the held Plate or type-specific Z-Crystal
Protean	VI	A Pokémon with Protean has its type changed to the type of the move it is about to use This only works once each time the Pokémon enters battle^IX
RKS System	VII	Silvally changes its form and type depending on the held memory
Zen Mode	V	A Darmanitan with Zen Mode changes between Standard Mode (a pure Fire or Ice type) and Zen Mode (a dual Fire/Psychic or Ice/Fire type) based on its HP

Terastallizing

Main article: Terastal phenomenon

After Terastallizing, a Pokémon will change from its original typing to its Tera Type. It will keep the STAB of its old type(s), but will also gain STAB for moves of its Tera Type. If a Pokémon's Tera Type matches one of its original types, STAB for moves of that type will be raised to a modifier of 2× (2.25× for a Pokémon with Adaptability). It is also the only way that a Pokémon can gain the Stellar type.

In the spin-off games

Pokémon Mystery Dungeon series

This section is incomplete.
Please feel free to edit this section to add missing information and complete it.
Reason: Confirm if a Pokémon that has changed type (such as from Conversion or Color Change) gains the terrain abilities, such as a Water-type Pokémon able to walk on water, or a Ghost-type Pokémon able to go through walls

In the Pokémon Mystery Dungeon series, most of the available moves and Abilities that change a Pokémon's type simply work as in the core series. The temporary type changes last only in the current floor of the dungeon.

Prior to Gates to Infinity, the move Conversion 2 caused the status condition of the same name for 11 turns. If the Pokémon with this status condition is hit by a move, it will turn into a type that has the best matchup against it (even if it's a non-damaging move).

In the anime

Arceus changing into a Ghost type with Multitype

Gladion's Silvally changing into a Dark type with RKS System

Leon's Cinderace with its type having changed to Ground via Libero

In the anime, the possibility of changing types was rarely mentioned onscreen prior to Pokémon Journeys: The Series, with the notable exceptions of Arceus and Silvally, whose Abilities—Multitype and RKS System, respectively—are integral to the Pokémon's biology and, as such, were heavily featured when the Pokémon was battling.

Several moves and Abilities that change Pokémon's types in the games have appeared, but are not known to do the same, in the anime:

Conversion (Japanese: テクスチャー Texture) has the user copy the target's color and texture. While unconfirmed, Conversion appears to alter the way the user is affected by opposing attacks, as if its type also had changed.
Transform has been used on multiple occasions by Ditto and Mew, turning them into a copy of the target and allowing them to use moves from the Pokémon they copied.
Camouflage and Color Change work similarly, turning the user invisible.
Zen Mode changes Darmanitan's form, but the type change included in this process has yet to be explicitly mentioned.
Relic Song does not appear to deal damage, but still changes Meloetta's forms, affecting its battle style and available moves, and it makes plants grow as well.
Forest's Curse binds the targets with vines from below.

The type-changing Abilities Imposter, Protean, and Mimicry, as well as the moves Conversion 2, Roost, Reflect Type, Soak, Magic Powder, and Double Shock, have never been shown to be used in the anime.

Despite Soak having not appeared in the anime, its effect of turning the target into a pure Water-type to allow Electric-type attacks to hit Pokémon normally resistant or outright immune to them, like Ground types, have been directly referenced in A Grand Debut!, after Ash's Pikachu drenched Hapu's Mudsdale in seawater, allowing him to finish the battle off with a Gigavolt Havoc. This effect can be traced even further back to Showdown in Pewter City, prior to the move even debuting in the games, when Ash's Pikachu defeated Brock's Onix with an Electric attack after the Rock Snake Pokémon had been doused by the sprinklers.

Pokémon the Series: Diamond and Pearl

In Arceus and the Jewel of Life, Arceus changed between types with Multitype. This marks the first time a type change is confirmed to have happened in the anime, as Arceus changed into a Ghost type to turn itself immune to Palkia's Aura Sphere.

Pokémon the Series: Sun & Moon

In Mission: Total Recall!, Gladion's Silvally changed type for the first time using the RKS System, turning into a Dark type with the Dark Memory. It did the same with other Memories throughout the rest of the series.

Pokémon Journeys: The Series

In Advice to Goh!, a wild Moltres lost its Fire typing after using Burn Up.
In The Arceus Chronicles (Part 4), a wild Arceus changed into a Water type with Multitype.
In Pride of a Champion!, Diantha's Gourgeist used Trick-or-Treat and added the Ghost type to Lance's Gyarados, allowing Gourgeist to deal more damage with its Ghost-type attacks. It also did the same with Lance's Hydreigon, though this didn't come into play at any point.
In A Flood of Torrential Gains!, Leon's Cinderace had its type changed by Libero for the first time: after using Scorching Sands, it became a pure Ground type, making it immune to Ash's Pikachu's Thunderbolt.