I was temped to make a thread just for this question, but I figured that'd be a waste, so I'll ask it here: What characters would you actually want to see get the deluxe costume treatment a la Sans and Cuphead? Basically, a character that would work as an all-concealing Mii Costume, and who comes with a music track from their game.
One that immediately comes to mind is Shovel Knight (Mii Swordfighter), with the song 'Strike the Earth!'. Given his status as an Assist Trophy, it seems pretty unlikely that he'll be added as a DLC fighter, so I think this would be a good compromise.
Another one that comes to mind is Miriam (Mii Swordfighter) from Bloodstained: Ritual of the Night, with the song being either 'Voyage of Promise' (the Galleon theme) or 'Luxurious Overture' (the main castle theme). Since Miriam is typically very stoic, her face wouldn't be too off-putting as a mask.
I would also love to see a costume based on Madeline (Mii Brawler) from Celeste, with the song 'First Steps' (the song for the first level, Forsaken City). I've gotten a good deal of the way through the game, and I've liked what I've played thus far, so I'd be really happy to see it get some love in Smash.
Yooka & Laylee (Mii Brawler) would be cool as well. Given how chill the music for the game is, I think that they'd have to make a more energetic remix of the main theme. The Yooka head would have Laylee sitting on top, and it'd jiggle as you move.
So, any ideas?