If Wishiwashi is level 20 or higher, at the start of battle or the end of a turn, if its HP is above 25%, it will change into its School Form. At the end of the turn, if its HP is below 25%, it will change back to its Solo Form.
Role Play, Gastro Acid, Worry Seed, Simple Beam, and Entrainment fail if the target has the Ability Schooling. Skill Swap fails if either Pokémon has Schooling. Schooling cannot be copied by Trace, Power of Alchemy, or Receiver. Schooling cannot be replaced by Mummy or suppressed by Core Enforcer. If a Pokémon other than Wishiwashi obtains Schooling with Imposter or Transform, the Pokémon will not change forms.
Outside of battle
Schooling has no effect outside of battle.
Pokémon with Schooling
Types First Ability
Please note that this is only 100% accurate to Generation VII games.
For Generation III games, ignore Abilities introduced in Generation IV or later and Hidden Abilities.
For Generation IV games, ignore Hidden Abilities.
For Generation V games, ignore Abilities introduced in Generation VI or later.
For Generation VI games, ignore Abilities introduced in Generation VII or later. In the manga
In the Pokémon Adventures manga Trivia
Schooling is the only Ability that requires a certain level to activate. In other languages