Volbeat

Volbeat is one of many mediocre Pokemon blessed with a fantastic hidden ability. With Prankster granting it priority on all non-attacking moves, including a buff to its near-signature move, Tail Glow, Volbeat finally has a chance to function competitively by passing colossal Special Attack boosts to Pokemon that can actually use them. On the downside, it still has a very poor stat distribution and lacks the tools to prevent phazing attempts on its own, which makes a successful setup rather difficult to pull off against a well-prepared team. All things considered, Volbeat's performance is directly akin to the strength and fortitude of its teammates--don't let your guard down for a second, or you may find yourself on the losing end of a sweep.