Nikushimi

Vs. Orochimaru (Normal): Kakuzu wins with some difficulty. Kurogane Karada is his main advantage here.

Vs. Orochimaru (w/ Manda): A much closer fight. It could really go either way, but I'd have to give the win to Kakuzu, barely.

Vs. Oohebi Orochimaru: Kakuzu wins this fight probably the easiest. Since Hidan's ritual didn't kill all five of Kakuzu's hearts, I'm guessing each one circulates different blood (although, to be honest, it could simply be that only Kakuzu's Suiton heart was affected because that was the only one that was truly his; it depends if he kept his original heart or not, but I doubt it), which means that Oohebi's paralyzing blood vapors won't necessarily incapacitate Kakuzu. Or if they do, he'll have five chances to figure out how to avoid getting duped another time. Kakuzu's Taijutsu and Ninjusu suffice in completely overwhelming Orochimaru here.

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Bow to the King.