Hey, have you tried simple water buff stacking?

Haku is a must simply for the barrier to boost water ninjas, other than that i'd recommend Ten-Ten for the crit increase, damage mystery & 10 hit trigger and either Suigetsu or Mist 7 Zabuza as both attack twice each turn i'd recommend Suigetsu as he has a damage mystery.
Lineup -
Suigetsu - Haku - X
Ten-Ten - Main - X
X - X - X
Skills - 2-3-1-1-1
Summon - Ton Ton
You want elemental damage hence the Shark Bomb and Water Whip, clone gains water buffs and deals elemental damage as well as giving 20 chakra when it dies.Skill Order
Round 1 - Haku Barrier before you start attacking
Round 2 - Shark Bomb, Suigetsu Mystery
Round 3 - Wait until Suigetsu attacks then use Haku Mystery this ensure you get maximum damage out of buff, after it goes off spam Haku barrier when Kyuubi is about to attack you (this lets you recast the barrier before round 4
Round 4 - Use any remaining mysteries and try to retreat before tailed beast bomb.



If you do end up trying let me know how it turns out, im curious myself as i've tried a similar line up just haven't had awakening/cultivation to maximise it.