Ok heres the simple fact, Kisame maybe a real power house but he has one great disadvantage in this matchup...orochimaru seemed to have intel on everyone! Im sure oro knows all about Kisames abilities and the best ways to counter them, while Kisame couldnt possibly know all oro has up his sleeve, with that being said lets look at some facts: oro has edo tensei, oro has quite impressive summoning abilities and poison which as far as we know Kisame has not proven to be an expert on. Yea I think oro is a safe bet