In theory, Drapion could sweep in OU, but it is greatly outclassed in the tier by Hydreigon. In RU, Drapion can hold his own as a bulky sweeper, but probably shouldn't be used in OU. Why make him look bad, when he has so much RU potential?
Hydreigon @ Choice Scarf
252 Spd / 252 SAtk / 4 HP