@BlackOsprey Unlike Demyx and Larxene, Sora is quite special with an unusually powerful heart that makes him stronger with the more people he connects his heart too and is a skilled and powerful Keyblade Wielder. So despite his childish and foolish personality, he'd be pretty damn useful to control.
@Vulpeus 1041 I say Vanitas and Riku Replica because they both appeared in KH DDD, what other reason would they both appear if it mean absolutely nothing? I just said Terra because Terra's status is confusing and unknown. But when Master Xehanort returned, he looked like his normal and regular self, not like Terranort for some reason. I also mentioned Master Eraqus' Nobody because I believe that one might have been created special like Namine when Terranort became Ansem and Xemnas. Think about it, Terranort was Master Xehanort's soul and heart, and Terra's heart (which contained Eraqus') and body since Terra's soul was in his armor (Lingering Will). We know Master Xehanort's heart became his Pureblood/Emblem Heartless known as Ansem, The Seeker of Darkness. Whilst Terra's body and Xehanort's soul became Xemnas.
But what happened to Terra's heart and Eraqus? Did the presence of Terra's heart leaving it's body create a special Nobody like Namine? Same thing for Eraqus? Are there two more Namine's out there? If so why haven't they shown up? All we know is that Xehanort said he had Terra in his possession but in which form wasn't really clarified and I still don't understand why Xehanort came back looking like his older self instead of being Terranort. I also say Marluxia because he was one the most mature, intelligent, and most powerful members of the Organization.