Pokémon Abilities

An ability is always on. Unlike a move, which you choose on your turn, an ability works in the background for as long as the Pokémon is in battle. Its effect can trigger the moment the Pokémon enters, every turn, or only in a specific situation, depending on the ability.

Each Pokémon carries exactly one active ability, even though its species may be able to have more than one. Abilities cover a huge range of effects, from raising a stat to canceling out a type matchup, which makes them a quiet but important part of how a Pokémon performs.

A hidden ability is an extra, rarer ability that some species can have in place of their usual ones. It often does something quite different, so a Pokémon with its hidden ability can play in a new way. Not every species has one.

Hidden abilities earned their name because they have historically been available only through special methods rather than from an ordinary wild encounter. The exact way to find one changes from game to game, but they are always meant to be a step harder to obtain than a standard ability.

In the modern games, yes. Items such as the Ability Capsule let you switch a Pokémon between its standard abilities, so if a species can have either of two, you can flip to the other. It is a simple way to fix a Pokémon that came with the ability you did not want.

Getting a hidden ability is handled separately, by an item called the Ability Patch. Which of these items exist, and how you get them, depends on the specific game, so treat this as the general shape of how ability changing works rather than a fixed rule for every title.