For a long while i used haku, suigetsu, guy, around up to level 73.

For f2p team the best in terms of damage per second i tried is asuma wind blade, tenten gnw, iruka with skewering, taijutsu attack, water style water trumphet, water enhancement, clone, summon tonton.

The best for pure damage have mei in wb asuma place with retreat after round 4, but due to early retreat and mei animation you lose a ton of time that makes it less effective in comparison with the other one.

If we consider also other ninjas you can swap out iruka for hashirama and wb asuma for tobirama or gengetsu. Are the only options i think could give a better outcome than the two before i talked about with the ninja we currently have.