I have a question for people. Since Sakurai is obviously trying to make each DLC character bring something new to the table and I think he's even claimed as much, do your most wanteds actually have the capacity to do so? For example, I know Rex talk has gotten stale, but I would like Rex (even though I'm unsure if Nintendo agrees), and one of his strengths is that Pyra and the concept of Blades provides some material for unique play mechanics.
My unpopular opinion is Crash, while iconic, I feel would probably have a basic b*tch moveset. I have a hard time imagining some kind of unique mechanic that hasn't been done belonging solely to him. If someone wants to prove me wrong, I encourage it.
-Adeleine can bring a new playstyle. Depending on how they implement her, I think she could get "persistent" smash attacks: instead of the usual stronger hit, her smash attacks would summon some creatures that will stay on the stage for a while. You can use them as traps and limit your enemies' movements with them. She can also summon bosses, and you could either remote-control them (Adeleine stays near the easel and you must protect her with the boss drawing) or ride them like in Star Allies (again, it depends on how they would implement her). There are other characters who can place moving/attacking traps on the stage (Pac-Man, Villager/Isabelle) and who can ride vehichles (Wario's bike), but none of them have a moveset completely built around that; remote control with a static weak spot would be completely new though, the closest thing is Ness/Lucas' up-b but that's just one attack and does not have its own small moveset like Adeleine's bosses would.
-Karate Joe would get some rhythm based moves, maybe his neutral special could be some junk thrown at him from the foreground and you have to hit them with the correct timing in order to throw them at your enemies. The most crazy concept I had for him was to make his moveset adjust depending on the bps of the soundtrack that's playing, and in case of those weird ambient sounds ones like in that Pikmin stage, you hear a metronome. It would be great to fight exactly by following the rhythm of the background music, but I think that it would be hard to implement with input lag, move buffer and especially online play.
-Ganon... he would not be much unique Imo... it's just a big monster on rampage. The thing is that he's already big, but he also has a trident that allows him to hit even bigger spaces than how he already would with his own arms only. That could end up being unbalanced maybe? probably... though I would like to see how the developers would solve this problem without losing the feel of being in control of a huge destructive beast. If we add magic though, he can get some more uniqueness... maybe use some Dark World portals to move through the stage and summon that energy orb that can be sent back by attacking it with the right timing (kinda like Gordo but more auto-aiming and easier to hit to keep the ping-pong match going).
-Cpt Syrup, I'm not sure. She would be a character with a moveset almost completely made up from scratch, so it depends. I honestly think that she would stand out more for her personality and style than for her gameplay uniqueness though (think of someone like Cpt Falcon).
-Hornet from Hollow Knight. This one depends on how they implement her. In the worst case she could end up being a semiclone of Zero Suit Samus with a fire emblem counter and a long range nail attack, but my hope is that instead they base the character more on the concept that she can use her nail and rope as a way to move faster in the air: so, hit a wall to fastly travel toward it; hit the floor to fastly stomp down; hit an enemy (maybe with auto-aiming) to fastly fly toward him/her. She can also use her rope to place (static) spiked traps on the stage and limit the movements of her enemies. Also, Silksong will expand this character with new skills and items (there should be a crafting feature too) so she could end up being way more unique than we think.
Here's an idea then. The last character you played as is playable, and their homestage is the last stage you played, who is it? For me, it'd be Rouge the Bat and her homestage is Security Hall from SA2. Not the Sonic character I hoped for tbh
The knight from Hollow Knight, the stage is the Godhome. Not bad, but I would prefer Hornet.