Quoted By:
Most of the time running four attacks is fine. A lot of support moves that are used in competitive play only matter in a format where both players have a full team, aren't programmed to mindlessly click the most-damaging move (ideally...), and you can't use healing items.
That said, sometimes status moves can be pretty darn helpful. Take pic related from BW for example. It learns Hex, a fairly weak attack that doubles in power if the target has a status condition. It also learns Will-o-Wisp, which burns the opponent. Yamask here benefits from already having a bulky build, and with WoW it becomes even more durable and able to deal out better damage. Thunder Wave is also an almost-always useful nondamaging move, especially if you can pair it with Electro Ball.
