Hah and yet tsunade couldnt even kill oro without his hands , that should tell you lot about the outcome of tsunade vs oroYou are wrong. In part1 it was stated only a Sannin can defeat a Sannin. And this was true until Sasuke defeated Orochimaru.
There is a Japanase myth and card game, where the Slug is afraid of the Toad, the Toad is afraid of the Snake and the Snake is afraid of the Slug. And we all know Naruto is based on japanase legends and myths.