The Six Paths of Pain
Obito does not have the Rinnegan yet or Juubi.
Akatsuki get some prep time to learn about Aizen before they make their move.
Setting Las Noches
Much as i love Aizen, with knowledge on his abilities plus the fact that the Pain bodies are arguably immune to KS, I'm gonna have to side with Akatsuki. He can probably take down most paths and maybe Itachi but not all of them. That is assuming this is base Aizen.
Pains bodies are not immune to genjutsu so KS would work.
Base Aizen wins.
@One_Piece_God: Oh yeah, Rinnegan can't see chakra flow as the Sharingan and Byakugan are able to.
But that still leaves Obito and Itachi, who are quite likely to detect the energy coming from Aizen's sword. That, and I doubt Aizen has a means of getting around Kamui or the Sword of Totsuka.
Wouldn't anyone with doujutsu (Nagato, Itachi, Tobi) be capable of seeing through Aizen's illusions?
You brought up an interesting point. I don't see why they couldn't honestly especially with verse equalization.
I don't think he would allow Chibaku Tensei to even happen, much less get caught in it.
I don't see how he has a choice in the matter. The Akatsuki have something on their side Aizen lacks, teammates. Even if he has the capabilities in defeating them individually, it would be long too late to stop Nagato. Base Aizen would have it worse seeing as he lacks the firepower to blow his way out as othus suggested. Obito and Itachi are still sufficient enough to pull off a team effort and hold him at bay, especially with knowledge and prep. Aizen is cool, but you guys are giving him a little too much credit.
@nishi99: If he has the Hogyoku, he should win because of immortality
Can use the same argument for Hidan so thats not really a viable statement.
But basically Aizen wins this with mid difficulty even in base he is just too damn fast for ANY one in the akatsuki other than Obito. & even he cant scratch him.