kimmi def takes it his bon defense was enough to stay alive under gara sand burial if that what it was called so i dont think zabz would even be able to cut kimmi and i guess if he caught him in his water prison jutsu the kimmi might drown but with the bracken dance i think he could brake that jutsu np
Kimmo with mid-difficulty, his taijutsu and dense bones would maneuver around Z and deflect his offensive attacks. Also, curse mark form would be a lot to handle.
Kimi has bones of steel to protect him from Zabuzas sword which would be the only means of killing Kimi.
Kimi can grow bones anywhere in his body such as directly under his skin which would negate Zabuza decapitating him. Hidden Mist also effects Zabuzas vision as well so as soon as Zabuza sees Kimi he will also be seen by Kimi and that's when the dance will begin lol.
Not to mention Curse Mark level 2 with that giant drill arm would destroy zabuza.