All online games have those few strategies which are overused by too many people that they become really annoying. They aren't cheap or cheats, but you just get tired of playing what seems to be the same people again and again. So far i'd have to say the two biggest things i've noticed were:
*hammer bros. deke and skillshot
*continual lob passing then quickshot
i don't mind them during a match, it's just when it's the only thing the other person does the entire time.