I'm a little perplexed with what people want the Zelda cast to be.
Link, Zelda and Ganondorf are universal and essential. Everyone rightfully thinks they should return.
Toon Link and Young Link are seen as superfluous. This makes sense as both characters are derivative of Link. And even if you think having a child Link is important, you probably accept that only one should stay.
It's Sheik where I becomes confused. A lot of people say she is expendable and should be among the first cuts. She's largely a one off character with only big celebration games like Smash or Hyrule Warriors bringing her back. I suppose I can understand not wanting one off characters in franchises that aren't built off of rotating casts, but then people push other one of characters like Midna and Skull Kid.
Midna and Skull Kid aren't bad choices in my eyes. They're both one off characters, but they're incredibly popular and are from monumental landmark games. Their resumes are incredible and they are some of the most beloved characters in their franchise. Many characters would be happy to have that on their resume.
Thing is Sheik has all of that, and is a long time Smash veteran with a very rich competitive history.
So, I have to ask what you want the Zelda roster to be? Just the essentials of Link, Zelda and Ganondorf? Should one offs be included too? Or should it only be reoccurring characters like Impa and Tingle?
I personally think a roster like
and Skull Kid / Midna (with Ganondorf and Toon Link decloned) would make a lot of Zelda fans happy and would arguably be ideal. Don't get me wrong. I love Impa and I would love to see her inclusion. But Impa and Tingle don't have the sheer pop that Skull Kid and Midna (and Sheik) have.
I think any unique non Triforce wielded newcomer would be positively received but we need more characters like Sheik. And I think removing Sheik for a character like that misses the point.
First, yeah Link Zelda and Ganon the Dorf are absolutely musts. While I like them as they are, I wouldn't mind them getting redesigned after newer games. Link can fuse his bombs to his arrows, Zelda's phantom is reflavored as an eccho and her grab is turned into her linking ability, and Ganon gets gloom effects on his attacks (sadly, if you lean into Ganon's TotK look you can;t give him his incredible cape deflector.)
The biggest reason people are anti Sheik, at least from what I see, is because she can be easily replaced by Impa who is a much more consistent presence in the series. She's like the only reoccurring character in the series left besides.... Tingle? Beetle? Epona??? I think Impa could slot over pretty easily onto Sheik's moveset, hopefully with her SS design because I think she looks cool. Maybe change one of her specials into something involving the Lens of Truth. Law in one of the One Piece fighting games has a move where he can create a circular area around him where, if the opponent enters it, all of Law's move connect no matter what. I imagine it working like that.
I do think the toon-series of games should be represented, but if I could choose any character for it then instead of Toon Link I'd go with Tetra (yes, I see the irony of saying we she cut Sheik, who is just a version of Zelda, for Tetra, who is another version of Zelda). I just like her pirate look, I think you could lean into that for an interesting moveset. Her normals would have her use the knife on her model, she could have moves involving the ship attachments like the canon and the salvage crane. You could also let her use the wind waker items that Toon Link doesn't get to use, like the grappling hook and the skull hammer. For some reason I imagine her having a move that summons a hanging lantern on a rope that swings around like Maria's power line move from Jojo's HftF.
Final Smash? Her crew puts the opponent in a barrel and launches them from a catapult.
Midna, to be completely objective, would be sick as hell. She could ride on Wolf Link (yet another link on the roster), and her big hand hair could make her a cool rushdown/grappler mix, and we don't currently have any female grappler characters on the roster. And I know Sakurai likes doing this a lot, the Twilight power effects would look cool as unique hitsparks.
For Skull Kid, we all know what his final smash would be, he makes the Moon Fall. Classic, iconic. I have no idea what the rest of his moves would be. He has a trickster god aesthetic going for him, like a Loki-esque look, but i can't help but imagine it'll get interpreted as generic purple magic blasts. He curses a lot of characters is MM, so it'd be cool if every character had a special cursed-form like some moves in Darkstalkers, but I doubt that'd happen. However, Skull Kid and Midna have such simmilar support I feel it'd be weird to add one and not the other.
Midna and Skull Kid are the obvious front runners for any one-off character, but I have been die hard in favor of Guardian from Breath of the Wild. Now, I started supporting them before TotK released and I thought they would be coming back, but still. I want guardian to crawl around on testicle legs. I want them to be absolutely giant, like the biggest character in the game. I want them to be this imposing terminator character that can shoot giant lasers. I want one of their legs to be able to get broken off and they can pick it up and throw it. I just like big robot characters. If Guardian has one supporter, it's me. If Guardian has no supporters, I'm dead.
So to answer your question, I think the necessary zelda cast is Link, Zelda, Ganondorf, and Impa. If there's room after that, I'd add Tetra, Midna, Guardian, and Skull Kid in that order.
But consider... after Piranha Plant got added, we have the opportunity to do something
really funny.