You know after thinking about it I should probably explain my choices:
Baby Mario- I never really found him to stick out among the other Mario characters, there’s nothing really unique that defines him besides being a smaller, more annoying Mario, also it would just be weird beating up an infant.
Sylux- I admit it has a bright future but it’s nowhere near as important as Ridley or Dark Samus, and doesn’t have nearly as much personality as other characters on the roster to make it more appealing.
Magolor- If we’re gonna get another Kirby character, it should be Bandana Dee, and while I acknowledge Magolor would be unique, he doesn’t nearly have the appeal or reoccurrence that Bandana Dee, or even characters like Dark Matter, have, and I wouldn’t mind if her was left in the gutter.
A Sun and Moon Character: I know people are not gonna be happy with this one (I’m sorry in advance Lampy) but we already have well over enough Pokémon now that both the Pokémon Trainer AND Pichu have returned, plus if we’re going off characters from the Ballot, a SUMO character would just stand out too much with the small selection of newcomers, though if we have DLC I wouldn’t mind one.
Any Fire Emblem character- The only exceptions to this are Lyn, cause she’s the fan favorite, Celica, cause she’s relevant and popular on her own right, and Chrom as an Echo. Otherwise enough is enough.
Medusa and Hades- Simply put it, both are canonically dead and the story has completely moved on from them, I’d much rather we got Viridi because she’s more relevant to the concurrent Kid Icarus story and would contrast well with Palutena.
Shadow- I never got the appeal of the character, he’s literally just an edgier Sonic and would be a waste of a third-party character. If they’re gonna go with another character from SEGA, they should go with Arle.
Chris Redfield- If we’re gonna get a RE character than Leon or Jill is the way to go, Chris just doesn’t stick out and doesn’t have the history that either of those characters, particularly Jill, have.
Heihachi- Ryu already does the fighting game genere justice, we don’t need another character in that same vein, just add Lloyd as the next Namco character.
Shovel Knight- Oh bother, I never got why he became such a popular request for Smash, he had one game that didn’t even do well in Japan and that’s it. I suppose that that one rumor (Which was actually a miscommunication) contributed to his popularity, but even still out of all the third-parties we could choose from, including Shantae, he is probably one of the ones I’m least interested in seeing just because of the lack of historical value he has with gaming as a whole.
Minecraft Steve- I wouldn’t actually be too upset if we got him since their’s merit, it’s just his fanbase’s mentality that could ruin his inclusion is all.
Sans Undertale-
Okay but in all seriousness, similar reasons as to why I don’t want Shovel Knight... As well as a fandom that actually gives Steven Universe a run for its’ money.
And that’s that, some may agree some may not agree, these are just my opinions. Hope you have more insight!