well first of all i think pein can take on nine tails naruto and defeat him. we know sasuke can suppress the nine tail chakra but that is up for debate, also madara can also suppress the kyuubi chakra. we know pein is stronger than tobi who claims to be madara or rather wants his power which i would guess to be the ability to control the bijuu. we know pein is stronger than tobi and sasuke so i say he can suppress the kyuubi chakra either with his eyes or some kind of sealing jutsu. once that's done naruto's a sitting duck.
I'm sorry but where is your evidence to back up the claim that Pein is stronger than Tobi (Who I still believe is Obito from Kakashi Gaiden). The only time they've even talked was before Jiraya came to the Rain Village and Tobi aknowledged that Pein was the leader and strongest of the Akakakaskuskusi (don't know how to spell it, sorry).