SO lets consider some facts. We know that orochimaru has been collecting DNA's of legendary warriors to perform edo tensei. Oro knew this jutsu way before Kabuto's milk tooth grew up. Even during oro vs hiruzen fight in which oro used edo tensei. kabuto was just a kid who was competing in the kid's exam alongside naruto, sasuke, lee.
so what i am just saying is that no way kabuto himself collected all those DNA's and collected edo zombies he is using in this war. I think these speciments were already collected and prepared by Orochimaru but since his hands were sealed he couldnt used edo tensei any furhur so I bet kabuto stole all those DNA samples from Orochimaru's lab after Oro died and used them to make the edo's his.
In the same way since kabuto absorbed oro's DNA so he got a lot of physical boost and also a lot of knowledge automatically by absorbing oro's cells. Hence kabuto is just a thieve who stole Oro's body as well as the various DNA sample that kabuto used to make edo warrior.xd
so what i am just saying is that no way kabuto himself collected all those DNA's and collected edo zombies he is using in this war. I think these speciments were already collected and prepared by Orochimaru but since his hands were sealed he couldnt used edo tensei any furhur so I bet kabuto stole all those DNA samples from Orochimaru's lab after Oro died and used them to make the edo's his.
In the same way since kabuto absorbed oro's DNA so he got a lot of physical boost and also a lot of knowledge automatically by absorbing oro's cells. Hence kabuto is just a thieve who stole Oro's body as well as the various DNA sample that kabuto used to make edo warrior.xd