If it was a human being, not a zombie, in the condition Nagato was in a fairly light punch would kill him. You can't compare a sick human being to a zombie human, in fact that edo-tensei version of Nagato was most likely more powerful than pain and Konan combined. I'd see it beating the six paths personally.
Imagine if I gave a child the keys to a bulldozer, now the child knows what it does but it doesn't know how to use it. Now lets say I gave a strong man a sledge hammer and place them all in a back yard with a small shed.
I make a contest to see who can tear this shed down, and the strong guy starts knocking it down with his hammer. The little kid can't crank up my dozer, and after he loses, he says, "I couldn't get the piece of junk to move."
That's basically what happened with Nagato vs Itachi, Kabuto was like a kid in a bulldozer, even though the bulldozer is strong, if you can't use it then even a guy with a hammer will get more work done. Even with Nagato's immortality, he was being controlled by a novice of the rennigan.