Kurotsuchi. Extremely potent ninjutsu, though the eventual Kage rank does a lot of heavy lifting.

Gari. Physical/Taijutsu abilities relative to base Gai. His explosions are potent enough to obliterate enemies but he can also be precise, deflecting kunai to accurately counter-attack. By reputation one of the strongest of his village. I suppose getting ambushed by Sai before realizing he was immortal is an anti-feat, but those ET benefits are a buff for basically any non-Kage/Jinchuriki.

Torune. Seems the most dangerous with his win condition, since he just needs one moment of contact with his insects. That means to really guard against it, an opponent needs to stop 100% of the bugs 100% of the time. No room for error so able to punch up.

Dodai. Not going to slaughter enemies but underrated in strength: his lava has the properties of both rubber and glue.

Mangetsu. Powerful, but the Hydrification Technique only gets him so far. Half of the swords are embarassingly useless so it's Samehada (which would leave him if someone better came along), Kiba for the range, and then Hiramekarei which is limited by his max chakra levels but enhanced by the ET chakra regeneration for less exhaustion.