Lol these posts make me laugh,
First off, animal path alone, was way too much for jiraiya to handle, when preta and human path was added to the mix, jiraiya's strongest sage techs "super great ball rasengan" and "hair needle barrage" was proven useless, at which point jiraiya had to flee and come up with a strategy. fukasaku and shima sound genjutsu then failed when naraka path came into play. At this point jiraiya was done and luckily managed to take out animal path with the "toad gourd prison" tech. Thus jiraiya in fact did not battle all the 6 paths of pain, for the 2 strongest paths deva and asura had yet showed us anything, up until the pain invasion arc.
Naruto didn't defeat pain because he was stronger than him, pain simply needed him alive thus he could not use full force, thus if nagato had come to kill him he would've been dead. Therefore one cannot say naruto defeated pain so itachi can do it also, naruto had gotten help from hinata, fukasaku, frog summons and minato in that fight. Itachi by himself would get used, refused and abused repeatedly until he died, deva and preta path alone is too much for itachi, 1 amaterasu>-- gets absorbs by preta, tsukuyomi fails, because there is six of them, susanoo would fail because the bodies don't have souls (being there dead), thus itachi would have to find away to somehow defeat animal path summons, deva path chikaku and shrina tensei, and at the same time dodging asura path missile (which is locks on to the target even if they move).
Thus nagato is without a doubt superior to everybody in akatsuki in strength except madara.