This is arena fight and Kushina without sb was already a better ninja in those events compare to n6p.

Yup, I can second. I have almost full BT Kushina, and have no problem beating 100k+ above me sosp users. It also counters KKZ, so it's overall best of all 3 "metas".

How do you counter Kakuzu?

Kushina have more sustain and critical scale, so kakuzu land 0 critical when kushina deal nearly 100% when round 5+
+ kakuzu do 2 auto/round and myst. So with myst y+1 kushina c*e mystery every round

Kushina + one super armor breaker or clasical well knowm Edo Yagura Bkt this is the only setup that can outstand Kakuzu but unfortunatelly as how the game is at this moment the difference in stats is too big so Kakuzu is unstoppable as move 1. That's the saddest truth. Maybe over one year for casual player (players over 3 years playing) this setup may be reallly useful unless Oasis brings Refines and % tactics or other meaning to unbalance the game even further.

PS : You c*ways check Space-Time fights from next 6 months I will say between big spenders who will get that balance between moves 1-2 and you can see this in appliance.

Easy, make a suitable team with kushina and have her near full or full BT and go against some players who have 6p, Kakuzu, and other ninjas and you'll find out. If you lack power or the necessary stats needed for your ninjas then the results will differ.