From Bulbapedia, the community-driven Pokémon encyclopedia.
Hustle (Japanese: はりきり Enthusiasm) is an Ability introduced in Generation III. Eighteen Pokémon can have this Ability.
Hustle increases the user's Attack stat by 50%, but lowers the Accuracy of the user's physical moves by 20%. Special moves, Status moves, and moves that cannot miss are unaffected by Hustle.
Outside of battle
From Pokémon Emerald onwards, if the Pokémon with Hustle is leading the party, then Hustle increases the chance of battling a higher-leveled wild Pokémon by 50%.
Pokémon with Hustle
In other languages