The funniest part is, as VIZ later rectifies, Tobirama didn't 1 v 20 the whole Kinkaku unit. He was bait so the rest could ambush the 20 Kumo shinobi. Imagine being so weak that you can't even survive a little bit, as the creator of shadow clones & teleportation, before your students come to clear house.
Tobirama is a fat turd of a kage who is undeserving of his hype.