I just don't know. I might give it to Kisame if only because one of the few ways to beat Oro is to make him run out of chakra. And Oro almost solely uses a weird form of taijutsu (weird because his body bends and stretches) and Kisame is ideally suited for that because of his immense strength and Samehada. I mean Oro does other moves as well but not very often, he usually just attacks with snakes and rushes in to bite people or squeeze them or cut them with his sword.