Eh this is stupid. Kakuzu would have serious problems keeping up with sage mode -.- ' Naruto beated Kakuzu without it. Or Manda 2 could just crush him.
Without edo tensei, probably kakuzu high dif. Kabuto's major techs so far seem to revolve around crippling the enemy, which won't work against kakuzu's hearts. Those things proved that they can stay active when he's stone dead. Also if kabuto has suigetsu's liquification then he's probably also weak to lightning.