Well its like 9 tails, you need dmg boost and need some ninjas to make some combo
Sasuke/Guy/Iruka should work :)

Ye cat is kinda problem, you need to start combo every round to be able to do it and to have kinda huge dmg, expert gives max 180k so even if you dont kill it you get nice amount , but for experience you dont need special teams, pvp team can work :)

Well ye cat on extreme is kinda impossible to kill but anyway gives nice amount of coins