Anger Shell

When this Pokémon has more than 1/2 its maximum HP and takes damage from an attack bringing it to 1/2 or less of its maximum HP, its Attack, Special Attack, and Speed are raised by 1 stage, and its Defense and Special Defense are lowered by 1 stage. This effect applies after all hits from a multi-hit move. This effect is prevented if the move had a secondary effect removed by the Sheer Force Ability.