^ Apparently, Takara doesn't count either.
In that case, what kind of fight are we talking about? Are they just trying to kill each other, all means allowed? Because in that case, it depends on whether the Aria's can find the foxes' and Nii-chan's fatal verse. If they can, the girls are out of the game and Bon will beat everyone up; if they can't, Izumo's foxes will eat the bunch (except maybe Shiemi).
Who would win in a fight between Izumo and Shiemi, I have no idea. I have a hard time imagining Shiemi really attacking anyone, but her defences are pretty good. Probably a stalemate.