New update!
New characters: Freddi Fish and more FE swordfighters.
+ Updated opinions!
Robloxian/Roblox Kid: I HATE Roblox, and this game should stay the hell away from Smash.
Sans: Just because one game gets announced on Switch doesn't mean they should immediately get into Smash. (There are some exceptions like Crash Bandicoot) Also I just don't see him working in Smash, due to his Gaster Blasters seeming way too ridiculous and overpowered for standard moves. They seem more like Final Smashes. AAAAAAAND like another character on this list, I can't stand the fanbase. At all. Extremely toxic and stubborn, refuses to listen to other people's opinions without starting an argument or flame war.
Jynx: My least favorite Pokémon of all time. Enough said.
Goku (and all 4th party characters): Sakurai has stated that this is a fighting game for VIDEO GAME CHARACTERS. Characters from anime, TV shows, movies, memes, books, and other forms of media currently do not belong in Smash. This is why he allowed Mii characters in Smash in the first place: so you, and your favorite characters can all join the fight in some form. I stand by this rule because I have respect for Sakurai.
(If this rule was dropped by Sakurai however, I would love to see Steve Harvey, SpongeBob, and Xenomorph.)
Snip and Clip: Zero moveset potential and comes from a game that gives off a stupid/overly silly vibe similar to Freakyforms... no thanks. Also they function by cutting each other into pieces. That's pleasant.
Rabbids: Extremely annoying, and they would steal a much more deserved character slot from Rayman.
Baldi: OK, SERIOUSLY??? This isn't even a game in my opinion, rather a big, fat, ugly, mutated, pus filled, steaming pile of **** called a "game" that should never get representation in Smash. (That was a bit harsh... I apologize for the rant.)
Jonesy (Fortnite): OK, I do play Fortnite a lot, and I love the game, but what would this character's inclusion symbolize outside of being a dancing meme with guns? The moveset potential is there, but I feel like if this character got in, it would solely be for the horrendously toxic fanbase's demand... or the money. Same with Sans. It only takes about 2-3 games to run into a full group of screaming kids who rage and spout racial slurs every few seconds. (This is why I only play Fortnite with friends and family.) I'd be cool with an AT, item, or stage though.
Freddi Fish: I didn't even think about this character until someone in RTC brought it up, and then I realized how stupid and horrible of an inclusion she would really be. This character is from a game of the same name that is rated eC: Early Childhood, by the ESRB. That says it all. Freddi Fish is a game designed for small children for the sake of educational purposes. I played this game when I was three years old, and never played it again after that. We don't need characters designed for three year olds in Smash.
Insert Fire Emblem Swordfighter Here: It shouldn't be this way, but Fire Emblem representation in this game is horrible. Every single character wields a sword, all but one have counter as a down special, and 4 out of the 7 have Dancing Blade as a side special. That is awful, considering the FE games have so much diversity in fighter classes and weaponry. It's like Pokémon having mostly all fire types. We have 5 lords, a mage, and a manakete. Why can't we have an axe wielder, a pegasus knight, a dancer, an archer, a pirate, and more? There's so many different classes to choose, and barely any of them are being used whatsoever, with only one of the 3 weapons in the triangle being represented. (Unless you count Corrin's Dragon Fang) It makes me not want any more Fire Emblem characters, unless they carry something completely new and original to the FE cast in Smash. Pokémon has a ton of characters too, but at least they're all unique and have tons of special moves to use.
Those are my opinions. It's fine if you like any of these characters. I just don't want to see them in Smash.
Note: I'm sure there's good people in both the Undertale and Fortnite fanbases, this is just from personal experiences I've had.