Ao - A sort of Iruka-like ninja with double acupuncture and shield to fire/water attributed ninjas. Dmg is very low.
Sage naruto - Jesus Mary and Joseph this guy is OP. Rasen shuuriken does a ton of aoe damage and he can respawn his super tanky clone before every standard attack. Also +20 chakra before each standard attack.
Orochimaru - ranked battle God. *s at everything else.
Sasori - Super rare, summons millions of puppets, can't die unless you kill them all. Damage is very high.

All are surprisingly easy to get except for sasori. 5x 10 draws for each or there abouts.

She will come in the future, in the kage box.

I hope you're joking with that last question...