#sannins

During the 4th Ninja war I fully expected Kabuto to reincarnate Hatake Sakumo.

Unlike many other reincarnated shinobis used in the war it’s canon Sakumo’s grave is more off to the side, compared to the others, and therefore most likely also less guarded than the rest. It would have been easy for Kabuto to get his hands on Sakumo’s body, especially considering he was already able to get his hands on Asuma’s and Dan’s bodies, among many others. 

It’s canon Hatake Sakumo’s strength rivaled the Sannins’. Logically speaking it doesn’t make any sense why Kabuto didn’t reincarnate and use Sakumo during the 4th ninja war.