DSM Kabuto low diffs this because he has every counter. Assuming both sides have manga intel (which means Kabuto has all, Nagato has none)
If Kabuto begins with Hakugeki like he did against Itachi and Sauce, Nagato will repel it with ST.
Kabuto then follows up with Muki tensei and ****s him up, Kabuto rewrites his tag and the match is over.
If Nagato begins the fight with summonings (let's say they can fit the cave), he cannot summon the bird. So he's likely to use the chameleon for mobility/camouflage. Guess what? Kabuto has SM, he can sense the chameleon. Muki tensei destroys any summoning excluding Cerberus. Don't even waste your time trying to counter this point, Itachi got hit by it, that feat speaks for itself. The cave itself is too small as well. Again, waste of time.
Kabuto then traps Cerberus with Kidomaru's web. Nagato has lost every summoning.
Let's say Nagato begins the fight with Bansho Tennin which he has a history of doing. Kabuto shoots Hakugeki and Nagato has just lost because he's pulling in a 1 shot technique. Let's say he can't shoot Hakugeki...Kabuto uses Kidomaru again to shoot webs at Nagato. Gives Kabuto perfect prep time to use Muki tensei again and destroy him before he can get ST off.
If you think Nagato wins read my sig