Use this team:

Make sure to proc sixpaths dodge then use fire main myst on him. Use Itachi on the main character. Itachi will surely burst that six paths within 2 rounds. I am running Kurama KCM, Earth, Bee, and Roshi and I agree six paths is a problem in arena. Out of 10 fights that I had as earth main 7 of those are players running with six paths. As soon as I switched to this team, I won all fights against six paths. Good luck!