10- hidan/ immortality isn't everything lol
09- konan/ flight above immortality, since hidan can be disabled rather easily.
08- oro/ as far as durability and intelligence, he is farther up. unfortunately he is rather over confident to an extent.
07- kakuzu/ again, durability and his elements place him above here. but he seems slow to me and he is rather stationary it his fighting style.
06- sasori/ intelligence and multiple puppets+ poison is difficult to counter. take away his ability to use puppets, or an effective way to counter them and their poison, and he's useless/
05- deidara/ with his flight capabilities and clay manipulation skill, he is certainly a difficult opponent. arrogance and a short fuse are and was his downfall
04- kisame/ stamina, chakra reserves and durability+ loyalty to the ninja code make him easily one of the strongest characters without a bijuu or kekkai genkai.
03- tobi/ his kumui abilities have proven to be one of the most effective and talked about skills in the whole series. however without the rinnengan, he can't really put up much of an offense.
02-itachi/ his genjutsu is unrivaled, and his entire shinobi skill set is near perfect. his stamina is next to nill, so he is capable of winning almost every one on one fight with anyone. i don't see him being able to overcome nagato and his paths due to their being six and they all possess a doujutsu that surpasses his in some aspects.
01- pein; nagato/ i give it to him for being able to pretty much tackle all aspects of ninja arts without ever putting himself in danger. he has absolutely no mobility, but he doesn't need to. his six paths cover ninjutsu, taijutsu, summoning, chakra/soul absorption, mecha weapons, and revival. they have the best observation technique within any battle and the best coordinated attacks. if nagato is left uncovered, his paths are essentially immortal.