-Aizen is muken Aizen
-Madara is Juubidara with the shinjuu asborbed
-Madara and Aizen have full knowledge on eachother's powers, their pasts, and intentions.
-The 5 kage are the ones that fought madara
-The Gotei 13 and the vaizards are the ones that fought Aizen
-We are to assume that chakra is an immunity to spiritual pressure and allows chakra users to see and touch the shinigami
-All are in character
-Win by death or k.o.