This Ability inverts all changes to the stat stages of a Pokémon with this Ability; if an effect would lower a stat, it is increased instead, and if an effect would increase a stat, it is decreased instead. Effects that change a Pokémon's stats without affecting stat stages, such as burn and paralysis, are not affected by Contrary.
This also applies to self-inflicted changes, such as Curse and Leaf Storm. This Ability only inverts the changes when they are applied; it does not passively cause all existing changes to reverse; therefore, if the Ability Contrary is no longer in effect or the stats are passed by Baton Pass, all existing stat stage changes remain the same. Stats passed by Baton Pass onto a Pokémon with Contrary are not reversed.
Stat stage increases caused by the Z-Power effects of statusZ-Moves are not inverted by Contrary. However, the stat stage increases as a result of Extreme Evoboost are inverted.
Mist (including from Guard Spec.) and Flower Veil take into account Contrary's inversion before determining whether to block the stat change. For example, if a Pokémon with Contrary is targeted by String Shot while protected by Mist, it will gain Speed; if a Pokémon with Contrary is targeted by Swagger while protected by Mist, its Attack will not be changed.
If a Pokémon with Contrary uses Belly Drum, its Attack will be lowered to -6 stages (although the message will still say that the user maximized its Attack); if the user's Attack is already at -6 stages, Belly Drum will still deduct HP. Even if the user has Contrary, Belly Drum fails if the user's Attack is already at +6.
If a move used by a Pokémon with Mold Breaker, Teravolt, or Turboblaze would change a stat stage of a Pokémon with Contrary, the change will not be inverted.