I don't feel Sage naruto is OP at all, he's fine as he is but Mei I do feel is a tad on the OP side.

She has far too much in her kit imo, Ignition, Immobile, Acupunctre, Passive Barrier, Poison, Self Damage Boost, Strong AoE Mystery.

A tad on the OP side but not much and as stated before a control team is good against them