Root of warrior in that team is useless, you have jinpachi that removes 1 layer of debuff + azure fang standard attack if needed. On the other hand azure fang, differently from midnight blade, boosts tobirama ninjutsu, that is his best stat by far and where the damage comes from, and has the chase to let tobirama hit 30 combos even if jinpachi fails due to evasion and gives to tobirama chase also the poisoning effect. Remember also that if you use MB mei does not boost your main and if you use darui jinpachi is not boosted and you have no ccs. On the other hand Shark bomb hits all the targets + starts a 7 combo streak that also immobile thanks to mei and also ignites and poisones thanks to jinpachi and main. I do not see how the lightning main version may be comparable in quickness killing.

P.S. do not undervalue neither also the other option he suggested. I would actually use mangetsu in the place of mifune and hope in that 3/4 chance that chojuro is selected because 3 standard attacks of a chojuro with 9 water characters on the field you have no idea how much hurts overall if that chojuro is stacked at 70k+ (his standard attacks repulse...) and in round 2 with 80 chakra basically chojuro mystery + shark bomb nukes whatever is left alive.