For me, Kushina is good, and better if she's 3star(Gains Immunity). Her mystery skill is quite good as it has a cancel kinda debuff and the animation of her running towards the enemy and hits like a baseball player with her glorified frying pan of love is really funny XD I currently using her in my extra account together with Minato4thHokage and GaaraKazekage, WindMain Class.. And im rolling in arena smoothly :D