Try Minato / Water Main / Utakata. You need Poison Tai.

Minato tags an opponent -> Minato Mystery on Tagged Opponent -> All enemies that are susceptible to debuffs are now tagged and Poisoned; any mysteries that started to cast but have yet to go off are interrupted -> Utakata mystery for AoE Poison burst damage on up to 9 ninjas.

Mei and Hanzo are both solid picks for that last spot.

If you're going to run this team alongside a friend, make sure they c*so cause/benefit from Tag (Black Hidan, Konan, Ay, etc.)