From Bulbapedia, the community-driven Pokémon encyclopedia.
Stall (Japanese: あとだし Going After) is an ability introduced in Generation IV. Only one Pokémon has this ability.
Stall causes a Pokémon with this ability to strike last within its priority bracket. Therefore, a Pokémon with this ability will move after other Pokémon using moves with the same or higher priority during a turn of a battle. Increased priority moves will always go first, whether or not the move is used by the Pokémon with Stall. If another Pokémon uses a decreased priority move, it will go after the Pokémon with Stall.
The items Lagging Tail and Full Incense override Stall, and cause their holders to move after the Pokémon with Stall. If a Pokémon with Stall holds Lagging Tail or Full Incense, the item takes effect and Stall is ignored.
Stall overrides Trick Room, causing the Pokémon with Stall to attack last.
When two Pokémon with Stall are in the same battle and use moves in the same priority bracket, the Pokémon with the higher Speed stat will move first.
In Pokémon Mystery Dungeon 2, a Pokémon with Stall only attacks foes that are directly in front of them. This does not affect leaders.
Outside of battle
Stall has no effect outside of battle.
Pokémon with Stall
No Pokémon have Stall as their only ability.