Here's a team anyone with 400 scrolls can field that I've had success with. Redundant ignites and using both Roshi and Sage Naruto's mysteries in round 2 go a long way. I use 3 2 3 2 2 dog of hell and put all of my best gear on roshi. Tobi's mystery with the poison tai talent can do a solid 5k damage if you use it after their heal standards, and his chase ignites early in your combo to prevent a lot of Sakura's healing. His chase also continues dishing out damage to Roshi in late rounds.

Arena is a completely different meta due to the relative differences in damage and life.

Came across it in spacetime so I thought I'd post the results here. This is 82200 power vs 83900 power, with all of my best gear stacked on roshi (even to the extent of having some life magatamas and initiative runestones on roshi be 2 levels higher than those on tobi)