• Vaati could also appear in the other timelines, preferably in the Toon timeline because the Failed Timeline just seems like a place for Nintendo to dump the earlier games, since we haven't had a game in that timeline since the Oracle games. However, I would like to see if the Palace of the Four Swords is canon, because that could present some possibilities for revisiting the FT.
• Ganondorf is most deserving of a return. His resurrections in the Failed Timeline make no sense, if only because the basis of Adventure of Link and the Oracle games are that his minions are trying to revive him, even though it should happen anyway, unless his resurrection takes a long time and the games that focus on actively reviving him are supposed to speed up the process. He hasn't been in the Adult timeline since Wind Waker, and since he's had more appearances in the other timelines, another appearance in the Toon games would be nice, especially after the utter blandness of Bellum and Malladus.
• Majora's Mask should definitely have its backstory expanded upon, although I stand by my theory that "Majora" is the name of the tribe that created the mask. I need to read that article about the Dark Tribe on this site so I can see the possibilities there.
• Dark Link is just a recurring boss. I don't exactly want him to come back, but having him show up would be nice.
• I've only beaten the first dungeon in Link's Awakening, but from what I gather, Nightmare was meant as one-shot villain.
• Zant was definitely meant as a one-shot villain. The same goes for Ghirahim. Their only purpose was to serve their master, so there is no reason to bring them back.
• Veran and Onox were Twinrova's pawns, although I wouldn't mind them coming back.
• Bellum and Malladus are two of the worst villains in the series, if only because of how bland they are. I would like to see them again just to see their backstories expanded upon, although they're just expies of Nightmare and Ganon. Since I prefer Spirit Tracks over Phantom Hourglass and Malladus at least had some personality, I think Malladus is more deserving of a return than Bellum.
• Demise should definitely return, if only to bring the cycle of reincarnation full circle.