When an opposing Pokémon raises its stats, the Pokémon with this Ability will also raise the same stats by the same number of stages as the opposing Pokémon.
This Ability does not activate when an ally Pokémon raises its stats, or when an opposing Pokémon raises its stats through Opportunist. Opportunist will trigger if an ally Pokémon uses Swagger or Flatter against an opposing Pokémon, after the confusion is applied. If multiple triggers happen at once (for example, Torch Song used by a Pokémon holding Throat Spray), Opportunist will sum them up.
Outside of battle
Opportunist has no effect outside of battle.