Well, this was pretty tough. Had to stop and think rather than just barging ahead as usual. There's a couple characters I don't really like, but I'd rather not say who exactly to avoid coming off as petty. Had to make sure I had an actual reason to take them out beyond personal distaste. I'd rather not have to explicitly take out anybody, especially if the deconfirmation stretches on to the DLC, but there's some characters I'd rather still have a chance and I need to take the heat off of them, namely Sol and especially Reimu.
First Party:
1. Sylux - The easiest choice to make. I think they're cool, but their entire thing hinges on the MP4 payoff, which just hasn't happened yet. The possibility can draw interest, but I don't think there'll be much substantial support beyond that until something actually happens
2. Tingle - A really divisive character; Half of everyone finds him funny and quirky and the other half finds him really annoying, to the point he has a trope named after geographically-lopsided hatred. I feel his infamous status might hinder him. Oh wait he's already dead? Guess I'll change. Bumping up Lyn to number two to make up for this and adding a new third vote to fill the void.
2. Lyn - It hurts having to do this, especially seeing as she was my first submission for the thread. However, between Fire Emblem's infamous reputation with swordfighters and us already having a katana-user in Takamaru, I fear that Lyn's popularity won't be able to push her forward. In addition, Fire Emblem has a lot of characters to pull from, and I'm interested in seeing who would get chosen in that scenario. I don't want to be the guy who kills off characters just to see how people react, but I'm curious as to who would be chosen without Lyn.
3. King Boo - The problem here is that we've already got a ton of Mario content spread throughout the series. With the addition of Waluigi, we now have no less that nine Mario characters, and you could easily count Yoshi and Wario in there too. There's also arguably Donkey Kong, which would bump it up to 10-12 characters. Even if Mario is Mr. Video Game Himself, that's still a lot of fighters, on top of massive amounts of content everywhere else. While King Boo would help represent a smaller spinoff, I feel like people might look towards a series with less/no representation rather than adding more to an already heavily-represented one.
Third Party:
1. Rayman - Most characters has either A: A notable legacy or impact that keeps them in our minds, and/or B: A recent release to keep that impact going. Rayman... Doesn't really stick out that much. It's interesting; He's sold over 20 million copies worldwide, but after Legends he just kinda dropped off. To rub salt into the wound, the Rabbids - Which used to be a part of his franchise - Have had more activity than he has lately. I almost feel kinda bad for doing this, but I feel like he just doesn't have the momentum he used to.
2. Master Chief - As a big Western FPS starring a green space marine, there's a fair bit of overlap with Doomguy. While I thimk they're different enough to coexist together, I'm pretty sure we'll only get one, and having both as options might drag the two down. There's also the whole thing about Halo not being on the Switch, which might bar him from support from those who put emphasis on Nintendo connections. Lastly, he's been a major frontrunner in the era of SSBU. I don't want to be the guy who just wants to watch the world burn, but if we have a job for a big Western game or a popular third-party, I'm curious as to who would be added if Chief was taken out of the mix.
3. Shantae - Placing her last in terms of submissions to avoid feeling like I'm doing this just out of bias towards another indie (coughReimucough), but aside from that I feel like she might struggle with an indie job, thanks to all the different options. Out of the three put up for submission, I feel like her merits don't stick out as much.
Shovel Knight became emblematic of the recent indie boom, got multiple amiibos - Quite an achievement for a non-Smash third-party - And got a mountain of cameos. Reimu's series is among the oldest notable indies, and when we're taking the fanworks into account (Which I honestly think she should, or else we wouldn't be considering her at all), it's arguably one of the biggest franchises out there in terms of sheer volume of content. Shantae's decently old and has decent popularity, but the other two just have more of those separate perks.
Hope I didn't come off as having something against Shantae, what with how much I wrote. It's just that I ended up dragging other characters into the mix and that ended up inflating her section.
Other characters considered were Phoenix, since we already have a Capcom character, as well as Doomguy and Scorpion, for their series' infamous violence and Western slant. The latter two were left out because A: We already have some fairly violent games in here already, even adding Resident Evil (Also known as Biohazard in Japan), and B: As a major supporter of a rather Japan-oriented series, discounting someone for being region-centric would be rather hypocritical of me. Besides, I've seen some people say region-centric characters would be better for the base game rather than the DLC, so this would be their best shot short of a region-centric DLC job.
Oh yeah, I mentioned Phoenix in the honorable mentions section too. He just got out-prioritized (or he out-prioritized them, given the job?).