Just remember that Jiraiya fought with the 6 pains without knowing that they were 6 and he killed 3 of the bodies, he was amazing, with a lot of jutsus and techniques. He never was a Hokage because he didn't want it. Jiraiya could manage the susanoo also, but this fight should be very difficult. About Kisame, Jiraiya could defeat him easily with the frogs ninjutsu, like Naruto beat the pain one that use chakra from the enemy.
I think that if Jiraiya had more information about Pain, the 6 bodies and everything, the fight could end in other way. About the Sword that Itachi have is probable that it works just in spirits and not in people in their own body.
It could be a very good battle.