I made a list of what I consider to be deconfirmed characters or rather characters that shouldn't be speculated as much as others, any feedback is appreciated
Any Character with a Mii Costume: Black Knight, Viridi, Ashley, Takamaru, Lip, Isaac, Zero, Arthur, Goemon, Dragonborn, Lloyd, Monster Hunter, "Altair", Travis, Geno, Saki Amamiya, Chibi-Robo, Custom Robo, Tails, Proto Man, Vault Boy, Sans, Cuphead, Toad, Skull Kid, Spring Man, Ribbon Girl, Ninjara, Knuckles, Heihachi, Bomberman, Shantae and Dante should all be completely ruled out at this point. There's also a minor addition with Dixie due to having a mii hat but I think I'll let that one slide since it's not a full costume and she's a popular enough request that she can't truly be ruled out yet. There's other mii costumes but these were the most noteworthy ones in regards to speculation
Any Assist Trophy: They are already represented in the base game with their own functions and we have yet to ever see one be upgraded to playable status, with Min Min's inclusion over Springman being the definitive nail in the coffin. Not a single one has a better chance of getting in over any other assist trophy and that's what they will remain when the DLC is finalized
Any character from a series that has already gotten a fighter as DLC: This includes Persona 5 (not really a series but only Persona related content was included and only Persona 5 got spirits), Dragon Quest, Banjo-Kazooie, Fatal Fury, Fire Emblem (Smash 4 is an exception because Roy was a returning veteran, not a newcomer), Arms, Minecraft, Final Fantasy, Xenoblade Chronicles and Tekken
Any Non-Relevant First Party Character: This is for your Bandana Waddle Dee's, Sylux's and Porky's who aren't deconfirmed necessarily but also have absolutely no reason to be put in now nor are popular enough requests to be exceptions like K. Rool or Banjo
Microsoft or Sony Owned Characters: Banjo, Steve, Cuphead, Vault Boy and Dragonborn have all been on Nintendo consoles prior to their fighters/mii costumes getting revealed, so here I'm referring to any characters owned by Microsoft or Sony (or by a company that either of them own) that has never appeared on a Nintendo console. Characters like say Ori are not ruled out in this scenario but characters like Master Chief, Kratos or Ratchet and Clank are
Non-Frontrunners from Speculated Third Party Company Reps: This is basically for characters like Spyro in favor of Crash or Viewtiful Joe in favor of Phoenix Wright, etc. Any non-frontrunner or character that definitely won't be getting in before another character from the same company should be ruled out
Indie Characters: Shovel Knight, Shantae, Undertale and Cuphead were the most highly requested indie franchises to get a fighter in Smash and the most they got was a mii costume. No other indie character will come close to getting the same or better treatment than that (sadly)
Characters from Companies Already Represented in this Pass: Keep in mind I'm only referring to FP2, I think Sega, Atlus and SNK are still fair game, but characters from Microsoft, Square Enix or Namco should be ruled out at this point
Mortal Kombat Rep: The game is practically non-existent in Japan, has a 0% chance of getting in as a fighter
Any Third Party Franchise That Got Non-Playable Character Content in the Base Game or a Spirit Event: These include franchises like Rayman and Resident Evil
New Franchises That Got Spirit Events: These include Ring Fit and Astral Chain
A Bethesda Rep: Any Bethesda reps should be ruled out at this point, since it wouldn't make any sense to reveal Dragonborn in the mii fighter wave before what could potentially be a Bethesda character unless there's no Bethesda character. Plus the only option really left at this point is Doomguy and if Nintendo is negotiating with Bethesda, a company now owned by Microsoft, to get an FPS character, there's a certain green armored FPS character I imagine they'd prioritize over Doomguy
Any "New Game = New Character" or "Anniversary = New Character" That Got Spirit Events: Games like Origami King and Sonic's 30th Anniversary getting spirit events should rule out characters like this
Valve Characters: There's ambitious and then there's this. I'd love to be wrong of course but the only time Valve has ever been on a Nintendo console is when Chell from Portal was in Lego Dimensions and that was on Wii U
Another Fighting Game Character: It's not impossible that we could get someone like Sol Badguy or Ragna but all the DLC characters were chosen at once, I have a hard time believing Sakurai would pick Kazuya and then pick another fighting game character for the same pass, especially back to back.
A Zelda Character that isn't Impa or Tingle: With the series 35th anniversary this year, it's entirely possible the last character could end up being a Zelda character. I think what is unlikely however is that we get a character that hasn't been in several entries or been around for a while, such as the BOTW champions
Ryu Hayabusa: The head of Team Ninja (a company owned by Koei Tecmo who works on the Ninja Gaiden games) saying they're waiting for Ryu Hayabusa's invitation earlier this year is pretty definitive as far as I'm concerned