I was finally able to beat exam 70 at level 61 with around 12 750 power.I main earth with talent (from the top to bottom)1-1-2-2-3 summon chase/attack knocked down.My team was Guy,Naruto and Kankuro all 3 stars.Equipement at level 60 on all and refining(it help to go before them)...Position:

Guy-x-x
x-Naruto-Main
Kankuro-x-x

This took me a few try to get it to work on auto,there alot of RNG in this one and you need to go all offensive on Gamabunta(immune to condition). I had only Guy alive for the win and needed to survive the water attack (RNG) if you spread your team you get chance to have someone avoid it.(it not a 100%)

P.S.It my first post and hoping this help...