What would have happened? If Minato was still alive and Kushina had Kyuubi inside her and all the 6th Pain attacked the Leaf while finding her instead of Naruto.
I'm talking without Naruto, Tsunade AND Hiruzen, BUT the rest of Konoha like Kakashi, however not current Kakashi... Kakashi who fought against Pain.
Could Minato be able to stop Pain's CHOU Shinra Tensei or would Konoha be able to defeat all the Pain? This situation is just the same as when Tsunade was there, but just switched with Minato.
So, would Minato lead to others shinobi another way rather than what Tsunade did?
Contract seal > Asura (can't summon mechanical body parts), Animal (obvious reasons), Naraka and Outa Path (can's summon hell demon or demonic statue, or loses control of them if already summoned).
Also, Minato finger tracking technique will locate the real Nagato, if all else, the fact that he was able to not only sense Naruto from practically another country, but to also be able to ascertain particulars about his chakra (noted that Naruto had finally mastered the nine tails), and that he was able to sense and note particular difference between Madara and Obito's chakra as Juubi jin, is more than enough evidence that Minato could track the real nagato.
Only problem I really see for Minato is Deva Path, I think he can easily evade Human path, can't rip out a soul if you can't even tough the guy. Preta easily defeated with Hiraishin slash.
Deva, well, it depends, if Deva one shots with cho shinra tensei than he wins, however, if Minato survives cho shinra tensei, or if Deva has that 20 minute time out that he had in the manga, than Minato solos.
However, having said that, I think in a clear one on one where neither party has intel on each other, than it's pretty obvious that Pein-Nagato solos everyone except Tobi and Madara (coz a scenario where they don't have intel doesn't exist, they always knew).