IMO MB is just a Sasuke on steroids that can summon, he starts combos and keeps them going, what's worst is most of the ninja in the Kage Treasures have ninja's that are in perfect synchronization with him I.E Darui and Mifune. Both of these ninjas with MB and Root of Warrior is a threat. I personally faced this team quite a few times and just like any other team has a ninja like Sasuke, I always aim for that ninja since they are the center piece. Any ninja that can take away buffs I.E Mifune, BD, AF etc can easily render that team useless, have a few clones in as meat shields, use your debuffing ninja (in my case Mifune) on MB and BOOM! Enemy teams damage cut down by half, just because some players don't know how to deal with a ninja, doesn't mean it's OP.

Itachi Uchiha - "Every jutsu has a weakness, you just have to find it"