Strange Transmission Distant Shadow has the ability to use the techniques of anyone whos DNA is integrated into it:but you already know that...my theory is basically that...if kabuto(its only user) wanted to:he could 've integrated the DNA of every edo tensei he resurrected...plot hole?
Kabuto not integrating the DNA of all the shinobi he resurrected is not a plot hole. It's simply an unexplained event. It might be because he's compatible with only DNA of those he integrated in himself or that he is only familiar with the techniques of said people. But, this technique does have the potential to be absolutely broken.
I figured he could or probably has already done it. And yes, the technique is truly terrifying. But on a serious note, I do think Orochimaru would do such a thing, especially if he knows he can obtain the Rinnegan this way.
I've brought this point up in a thread way back. From what we've seen of Kabuto assimilating the abilities of the sound five and taka, does raise the question of why did he stop there? There may be some arbitrary limit he had at the time or simply because Obito moved up the 4th shinobi war, Kabuto didn't have the time to properly assimilate more abilities.
Could you imagine Sage Kabuto with Hashirama's wood release? Or Madara's Susanoo? Clearly there was more for Sage Kabuto to "attain", as was the reward he discussed with Obito for his contribution was to be Sasuke. Kabuto definitely had more potential.
Well the sound four were compatible for the merging, I mean they were compatible with Orocimaru's sage chakra (the curse mark), Kabuto implanted Orocimaru in himself so I guess he could implant even some parts of the sound four
Implanting other people maybe would've required to test the curse mark on them, but I guess Kabuto could adapt himself to them if he would, like he did with Orocimaru