Let me start by saying that I don't have a Switch, nor do I have any access to Smash...
But that doesn't stop me from having a wishlist! This list is mostly compiled from my own gaming experience. My top 5 are:
5. Shadow the Hedgehog (Controls the competition!)- The only character on my list who exists in SSB in any form, Shadow would make a good addition. While borrowing a few moves from Sonic, he could have an arsenal of weapons and unique Chaos Control powers that would put him closer to Bayonetta in gameplay.
4. The Spy (Backstabs into battle!)- This TF2 mercenary would wield his trademark knife, revolver, and sapper. He would have lower damage in order to compensate for his ability to cloak himself, as well as disguising as his opponent. His final smash could involve the other 8 mercenaries in a single, unified hit.
3. Spider-Man (Swings into the fray!)- The Friendly Neighborhood Spider-Man would have a variety of grapples and rappells, a lighter combatant with excellent recovery. Maybe Peter Parker didn't start as a video game character, but his recent PS4 title has brought him back into digital relevance.
2. Octodad (Nobody suspects a thing!)- Although his last release was a while ago, this floppy protagonist would carry over, to some extent, his ragdolling shenanigans from his own title.
1. Cuphead (Runs and guns!)- Fox isn't the only one with a blaster.
I'm curious to see what your top 5 are- not necessarily realistic, just your dream picks!