Evolution prevention

Evolution prevention refers to certain methods to stop a Pokémon from evolving.

In the core series games

B button

In the core series games, the player can press B during the evolution cutscene to prevent an evolution triggered by gaining a level in battle or by consuming a Rare Candy.

This works to prevent several methods of evolution related to gaining a level, including but not limited to leveling up at or above a certain level, or with high friendship, or in certain locations, or knowing a certain move, holding a certain item, and so on.

However, pressing B does not work to prevent evolutions from Evolution stones or from trades.

Everstone

Everstone

Main article: Everstone

A Pokémon holding an Everstone is unable to evolve using any of the methods triggered by leveling up. However, in Generation I, Pokémon: Let's Go, Pikachu! and Let's Go, Eevee! and Pokémon Legends: Arceus, the Everstone is unavailable due to the lack of the held item feature.

Only in Generations II and VIII, a Pokémon holding an Everstone is unable to evolve by using an Evolution stone.

If a Pokémon is able to evolve by trade with no held item, then it is possible to prevent this evolution by trading it with a held Everstone, except this does not work in Generation III due to a glitch, and additionally Kadabra still evolves while holding this item due to an explicitly programmed exception from Generation IV onwards.

Since the Everstone is the only method available to prevent an evolution by trade that does not require holding an Evolution item, it is not possible to trade the unevolved Pokémon in those games where the Everstone is unavailable or does not work on certain trade evolutions. For instance, in all core series games other than in Generation II, it is not possible to trade a Kadabra without evolving it into Alakazam.

In Pokémon Diamond, Pearl, Platinum, Brilliant Diamond, and Shining Pearl, Mindy offers a Haunter as an in-game trade in Snowpoint City. Since this Haunter is holding an Everstone, it does not evolve into Gengar.

Evolution exceptions

In Pokémon FireRed and LeafGreen, if the player does not have the National Pokédex, when a Pokémon in the Kanto Pokédex meets its evolution conditions but its evolved form is not in the Kanto Pokédex (for example, Chansey's evolution into Blissey), it will attempt to evolve but fail.

Some Pokémon are unable to evolve altogether despite the games being compatible with their evolved forms. This applies to the starter Pikachu in Pokémon Yellow, the Spiky-eared Pichu in Pokémon HeartGold and SoulSilver, the Cosplay Pikachu in Pokémon Omega Ruby and Alpha Sapphire, Pikachu in a cap from Generation VII onwards, and the Partner Pikachu and Eevee in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!.

In the manga

Pokémon Adventures

Yellow arc

In Can't Catch Caterpie!, Yellow reacted with shock and dismay when her Ratty evolved into Raticate due to the fact that she had no idea what is evolution in the first place. Blue then informed Yellow that it is possible to cancel a Pokémon's evolution by using the Pokédex.

In The Might of... Metapod?!, it was revealed that since Blue taught Yellow how to cancel a Pokémon's evolution, she had been often cancelling the evolution of her Pokémon by using Red's Pokédex. However, with the Pokédex no longer in her possession, several of her Pokémon evolved at once during the battle against Lance: Kitty evolved into Metapod and then Butterfree, Dody evolved into Dodrio, Omny evolved into Omastar, and Gravvy evolved into Golem.

In the TCG

In the Pokémon Trading Card Game, several card effects prevent a Pokémon from evolving. For instance, Spiritomb has an attack named "B Cancel" whose name refers to pressing B to cancel an evolution in the core series games.

This game mechanic article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games.