Madara, hashirama, minato, nagato, obito.
Why?
Madara+Hashirama = ULTIMATE POWERHOUSE. Plus, Hashirama has suppression powers for the bijuus. They will be the main force of attack. Perfect susanoo, in conjunction with wood release and hashi and madaras vast chakra reserves (as well as hashi's insta-heal), will prove to be difficult to handle.
Reason I put minato is because his FTG in conjunction with obito's space time would make them extremely difficult to beat in this fight. For example, let's say minato marks everyone. He can quickly port to one person, port to obito, and them BOOM, obito's intangibility allows for a quick way to survive. Since these two are one of the fastest in the series, this will almost always work!!! ALSO, minato has reaper death seal, the strongest seal in the series.
Nagato for his vast chakra pool as well as 2 other things: Chibaku Tensei (which would be insane at max power) + ability to resurrect!!!!! that's a very important thing to have in this fight. There's also the mazou too
Obito is used lastly for 2 reasons: 1: mazou and the 5 jinchuurikis and 2: ability to save others on the team by porting them away. If someone is in big trouble, he can make them intangible as well as put them in his dimension for recovery as well as nagato resurrecting.
Reason I didn't put Itachi is, although he has the greatest genjutsu, I doubt any genjutsu will affect So6P. Totsuka blade will be hard to use as well, and Death reaper is better in the long run.
ultimately, I don't know if it's even possible, but I think this team would be really good. What are your thoughts??