For those of you who read the most recent chapter in the manga (obviously those who have not should leave)
According to different accounts we have heard, Madara and Izuna were nearly EQUIVALENT in power
As we have seen with Sasuke and Itachi, people of like blood develop mangekyou sharingans with similar abilities (both sasuke and Itachi can both use tsukyomi, amaterasu, and susano'o).
Madara doesn't haven any special MS techniques (e.i Kamui, Koto Amatsukami). Given this, its probably a safe bet that izuna didn't either.
Any way, It appears that Tobirama defeated Izuna by a large margin, so even if madara is SLIGHTLY stronger than his brother, Tobirama still might edge out.
I am NOT saying that tobirama could defeat EMS madara, or madara with kyuubi, but i believe that Izuna DID have the ability to use tsukyomi, Susano'o and (maybe) amaterasu. Seeing that tobirama defeated Izuna, i believe it is safe to say that Tobirama CAN defeat MS Madara (I do not know if Perfect Susano'o is an EMS technique or just a MS technique, or whether Izuna could use it or not)
What do you guys think? i know its far fetched, but we don't know just how strong tobirama was (after all he WAS hashi's brother), he had a spacetime ninjutsu and we don't know how much weaker Madara is without izunas eyes.
Just tell me if you think my evidence is fairly rational or if not, why?