prime in our minds or prime from what we have seen in anime/manga? Cause the highest state i believe i've seen nagato in was his Edo form when Kabuto brought him back. if thats the case then Edo Nagato is kinda immortal ^^
3 hokages and Oro? .... im not sure because the edo zombie 1st and 2nd are not as strong as their original but prime hiruzen alone based on hype would be trouble by himself i think that unless he has full mobilty with the mastery like he has now he with paths he couldn't win
They have no answer for chibaku tensei it took 3 attacks (all of them OP) from arguably some of the top strongest characters of this manga..besides we don't know anything of hiruzen "prime"..nagato high difficulty.
If it were the paths I think it would be closer to a draw rather then a complete lose. Considering he can revive people to fight for him and having more then one person is a big help too.