FYI on Server 11, i reach around 11 million damage on the 9 tails event. When we kill him I get 1.2million xp and 2.3million coins.

That's the reason I am going to hit level 70 tonight. 9 tails is the best event in the game, and there's a reason it lasts so long. The longer the fight goes on for, the higher the rewards are for all those involved.

As for formations and best ninja choices - single target damage only, don't waste your time with anything that casts a heal or creates a barrier (unless it's Yamato who I use for extra damage vs 9 tails passive). Kakashi, lee, tenten, iruka, asuma, shurado, ANY of the swordsmen with x2 attack per turn passive.