Prankster

Prankster increases the priority of status moves by +1. This means that a slower Pokémon with Prankster can use a status move before the opponent uses a regular move. Or if the ability-bearer is faster, it could use a status move before the opponent uses a priority move like Aqua Jet. The move Quick Guard does not block moves whose priority is increased by Prankster (but it does block moves that already have increased priority).