Prankster is an ability from the Pokémon series introduced in the fifth generation. It allows the Pokémon to move first with certain moves.
Prankster raise's the priority of the Pokémon's status moves by one stage. In Generation V, it was not blocked by Quick Guard but this was fixed in future generations. In Generation VII, opposing Dark type Pokémon were immune to all moves that gain priority from this ability including attacks that change upon use like Nature Power. Moves targeting allied Dark-type Pokémon are still effective.