Suggested by Destroyer Fire Man’s flames could do a real number on Kakuzu if they were to actually land. Kakuzu’s stone hard defense is very useful, but Fire Man’s been shown to damage a robot with armor as potent as Mega Man’s. Still, this won’t end particularly well for him because Kakuzu is a lot faster and he also has more experience. There isn’t a whole lot that Fire Man can do to combat this Akatsuki member and that’s why experience can be just as useful as special abilities on the battlefield. Kakuzu wins.