I assume this is the same exact order of events, but with Tsunade?
Jiraiya defeated Human path with a single SM kick. Tsunade can take human in Base easily.
Asura path didn't show up until all 6 paths were present, but with 10% Katsuyu and any other giant Toads available could easily take down Asura, or Katsuyu could AT LEAST give them the durability to survive the explosions.
I don't know how Tsunade and Jiraiya could defeat Deva path, but seeing as how Jiraiya discovered Pain's secret while on his deathbed, canonically he could have found and killed Nagato especially with Tsunade as support, as Pain admitted.