I don't see it stated anywhere that he fought Hashirama with Rinnegan. And I really wouldn't underrate Hashirama even if Madara had Rinnegan at the time. Since both were descendents of the Younger and Old Brothers respectively. Hashirama Mokuton seems to be unparalleled compared to it's successors which were inferior i.e. Yamato, Danzo, Zetsu. Maybe Kubuto still has plans for Yamato as some point. I'm just wondering how much conciseness Kabuto is actually retaining, I feel Orochimaru will show up again at some point. And I wonder who this "Him" is. Assuming it's the Masked Madara.
Also, the way Madara and Muu are talking indicates that this isn't the first allied Shinobi army.
Well there was clan alliances before the foundation of villages so that could have been a precursor to the modern day Allied Forces.
All in all I have got to see Madara is just about as close to perfect in technique as you will get out of a shinobi. They are going to be pretty screwed if they can't find something to defeat him. Either Naruto is going to have to get some power ups again(either the "Strength" of the Younger Brother, maybe just maybe develop some secret Kekkei Genkai drawing it's roots back to his distant ancestors, or like I have said before awaken his own Rinnegan since his Tailed Beast Mode kind of draws comparisons to the silhouette of the Sage of Six paths.) Either that or Itachi is going to have to intercede at some point.