yeah I think Orochimaru would have made it more balanced.Wasn't Pain surprised by his sage mode, though? I can't quite remember. I would think if Pain didn't know of it, or much about it, then neither would Kisame, given Nagato was Jiraiya's pupil.
In terms of Madara, I dunno. there's got to be some weakness. When you have 2 hokages, a Sannin, and the often claimed "smartest ninja" Kakashi, you'd think they could figure it out.
Yeah I didn't mean that it automatically happened and there was no interference, it would obviously require help from Jiraiya, Naruto and Kakashi to fend off the rest while they do it, but I can't see Kisame and Kakuzu fairing too well vs Minato and Hiruzen, the 2 strongest ninja in the manga's history, at least, according to Kishi, working together.
Maybe I should have substituted Madara for Orochimaru to make it a fairer fight, I dunno. But I would think Madara has some way of being defeated.
I think Akatsuki takes this, 'cause they have a better chance of winning against their ideal opponents