And dirt. This tech needs a living host and ash and dirt. Also, from what I remember, Oro's tag didn't only make them under his control, but look more alive. When the Hokages were summoned, they had everything, except for proper colours. They were a bit decaying. XP
The tech that Oro and Kabuto use to bring back the dead required that the user uses ashes (from the corpse they want to revive? (idk?)) and living hosts (orochimaru used the sound kids) as material. When the corpses come back to life they have their original special abilites and free will, but with orochimaru's special seal, which he place inside the 1st and 2nd, they are rendered under his command.)
Dude. I know what you mean...But Kabuto did say that he has mastered it to a degree even higher than Oro and the Second Hokage combined. Either this is true or it's an illusion. The latter is extremely unlikely, though. So I'll just go with Kabuto being extremely intelligent and figuring out how to do it properly. :P
how the hell is this techique supposed to emmulate the previous user's abilities if Kabuto doesn't have any material from the previous users in the first place? For instance, what can his false Nagato do?