Anyone whose got the Rinnegan seems to have amazing skill and knowledge of it- with the exception of Kabuto of course.
Madara with Hashirama's regeneration is practically like his Edo Tensei self. He'll always heal, so he's going to have the invincible immortal title in battle. Of course he may not be able to beat aging seeing as he did actually age, but that's another topic altogether.
With Madara what you see with Edo Tensei, is mostly what you will get. Add in all Rinnegan, EMS, MS and Hashirama abilities and you've got Madara. All that together makes Madara too much for Nagato, healthy or not. Both have respectable battle analytical skill, however in the end Madara just comes out on top as even if their analytical skills are equal, Madara still has more in his arsenal to make use of.
Of course, if Nagato suddenly learnt he had Madara's eyes, then things could be different. However there's still Hashirama's abilities in this case which could make a huge difference. Unless the Rinnegan allows the user to use any form of jutsu, which we have reason to believe it does.
It wouldn't be a walk in the park, but Madara almost always beats Nagato; about 9/10 times.
