Ooh, I want to get in on the Zelda discussion too!
Zelda's definitely big enough to get a non-semiclone moveset. But yeah, the problem of who is a bit one. Zelda games are pretty varied, but there are a few standout side characters that have still left a mark.
Impa - Impa's the most recurring character, but she's really been nothing more than a Ms. Exposition until Skyward Sword (even then, she was only badass in flashbacks), and most of her support comes from her Hyrule Warriors appearance. Beyond those two, she's most often been seen as an older nanny to Zelda. Add to that the fact that most of her design is as a sheikah, and she's too easy of a Shiek echo. Yes, she could be unique. Just like all of our echoes could be. But Shiek!Impa would make more sense than even some non-echoes we have, so it's an obvious way in. As such, people who want more unique Zelda characters aren't that inclined to support her since she'd by nature be very similar to Sheik.
Skull Kid - He's probably one of the likeliest...if anyone ever gets a promotion. Majora's Mask did well enough, but of course it wasn't praised to the heavens since it had the misfortune of being the direct successor of Ocarina of Time. Still, there isn't a person on the internet who doesn't know the "24 hours remain" meme, so Majora's Mask is in the public consciousness. He could be incredibly unique compared to the current cast, and even has the benefit of having an iconic piece of headwear for Kirby. Considering the outrage when he wasn't included in Hyrule Warriors, and it's safe to say he's got a fanbase. Alas, he's an assist, and a decently hated one at that since his assist power is one of those that screws everyone.
Midna - Each Zelda game has fans and detractors. I think Twilight Princess was my favorite, but I know a lot of people hated the realism look so weren't sold on her. Still, she is the title character of that game, and had a massive fanbase since it came out - her assist came several year after her game had passed. She's got one of the most developed personalities of any Zelda side character, and also has the two forms as well, both of which were important in the Hyrule Warriors storylines. She's been one of my biggest choices since the Brawl era, and I wouldn't mind seeing her come back into importance. And now that the TP costumes for the cast are gone, it feel like something is missing.
Tingle - Loved in one part of the world, and loathed in others, Tingle's an interesting case. Yes, he's recurring, but is also known for his own set of spin-offs...which didn't get exports since part of the world just thinks he's the worst thing to come out of Nintendo. Tingle's a great example of how cultural differences are not necessarily universal, and with Smash being more cognizant of the Western reception, Tingle's probably dead in the water. I am surprised that his assist got cut though, that was decently inoffensive. I guess they thought that the Moon would be too many Zelda assists and decided to cut - I wonder if we'd gotten a Midna/Skull Kid/Ghirahim promotion if Tingle would have hung around.
Ghirahim - As important as Fi was, I feel most of the fanbase went to Ghirahim since Fi was basically Navi-the-waifu with the associated lack of personality, while Ghirahim oozed personality (among other things). Still, Skyward Sword was one of the weakest console Zeldas due in part to the awkward motion controls, so he may not have the sticking power of the above. As a villain, however, he is more memorable than Twilight Princess' Zant. Being one of the major characters in Hyrule Warriors also helped him steal the spotlight for himself. I wouldn't mind him - I'd prefer Midna first, but both would be great and unique additions.
A Champion - They were really good, and well developed with the Champion's Ballad DLC (and 100% should be added to Hyrule Warriors Legends as DLC with a BotW map!), but their issue is the fact that the game made all four equally important - that's even what Revali's entire storyline is - so putting one over the others would jsut feel wrong. It's weird enough that Daruk and Urbosa have primary Spirits while Revali's and Mipha's are supports. I can't see us getting 4 unique Zelda newcomers (but it'd be great), so they may not be able to hope for more than an assist that calls a Divine Beast. Compounding that is the fact that each has his or her own fanbase - and they don't all tend to agree. Mipha's the romantic and has a great weapon, but is never shown using it, has a very cliche story and a terrible VA. Daruk is a decently generic heavy, but is by far the most fun of the lot. Revali's got an abrasive personality which is already seen in Falco, but would also bring something unique to the table in terms of a weapon. Urbosa's the most generic in terms of moveset, but showed an incredible example of being a Bechdel-favored heroine. Now if it were me choosing, I'd go for Urbosa and be done with it, but I'd honestly love to see them pull a Bowser Jr. (even if it would require Mipha to get a growth spurt and be awkward for Daruk) and give each two recolors in one character - each race does have its entire set of weapons, and the four powers are good for specials, so it'd be a fun way to hit all of them.
If I had my way, I'd favor Urbosa first (what a great personality! By far my favorite BotW character!), then Midna, and then Skull Kid. But with all of the Zelda characters, it's tough to get a massive agreement like Ridley had.
Oh well, I will say the Skull Kid Mii is much cooler than I'd thought, and I do enjoy that at least.