Should target ninja who has the lowest HP.

Basically when you place your ninjas onto your team, that is the order of things happen such as buffs.

So if you say place Sage Naruto into your team first, his clone will pop up first. Then if you throw in Killer Bee as the 2nd one, it'll give the buff of all jinchuriki and his mystery should target Naruto.

All you have to do is make sure you pick up your main and place it as 2 3 or 4.