I think people are also forgetting that each generation UNTIL the 5th Hokage was revered as the more powerful than other Kages as in cloud, Rock and such Each generation of Kage was deemed or seen as more powerful than the other villges Kages.
Raikage was only beaten by Minato in Speed. Notice how no kage defeated a Hokage.
When he gave his life to the bounty hunters he could have did something to off himself and the hunters. Just saying we dont know the details.
Sasuke vs Tobirama no Orochimaru genjutsu release, woul be like the Allaince fighting Edo-madara, endless until sealed or the human being(s) he is fighting runs out of steam.
Without a seal team fighting an Edo is a losing fight. No matter if your Naruto, Sasuke or Hashirama.