Anger Shell

When an attack causes its HP to drop to half or less, the Pokémon gets angry. This lowers its Defense and Sp. Def stats but boosts its Attack, Sp. Atk, and Speed stats.

Crossing to half HP or less lowers defenses and raises Attack, Special Attack and Speed.

When attack damage brings this Pokémon from above half HP to half HP or less, its Defense and Special Defense fall one stage, while its Attack, Special Attack and Speed rise one stage.