Unburden

is an Ability that raises a Pokémon's attack speed if it is holding no item.

Effect
If the Pokémon has no item held, their attack speed is doubled.

Pokémon with

 * Hitmonlee
 * Treecko
 * Grovyle
 * Sceptile
 * Drifloon
 * Drifblim
 * Purrloin
 * Liepard
 * Accelgor
 * Swirlix
 * Slurpuff
 * Hawlucha