As mentioned earlier, all third-parties got cut as a mere premise.
Corrin, Incineroar and Piranha Plant were cut because they're terrible additions and shouldn't have been in Smash in the first place.
Even if keeping the OG 12 wasn't a rule I would've done so, great selection.
I initially cut Sheik, but decided to bring her back because I'd miss her, grandfather clause and to rep Ocarina of Time. Also considered either replacing her with Impa or adding both with Impa as her echo.
Dr. Mario and Rosalina got cut and made way for Toad and Waluigi. I feel like the latter two are much more important to Mario canon, and Dr. Mario felt like fluff that nobody would miss, while I hate how Rosalina plays. However in a hypothetical sequel to this roster's Smash I wouldn't be entirely against her return.
Cut a lot of Pokémon. Pichu and Greninja, while characters I like to play, just don't feel like they add a lot to the game, and Greninja especially I feel like his popularity has faded super quickly. Considered keeping Pichu as an echo, but decided against it.
Overhauled the Fire Emblem roster. Cut Lucina and Robin, both with reservations (I love the characters and feel like they're popular enough to make it in Smash) and inclinations (Lucina was the worst addition in base 4 to me, and I think Robin's moveset is terrible). Made Roy a Marth echo (since that's what he feels like), and completely decloned Chrom. Hopefully having 4 unique movesets and one echo makes people shut up about Fire Emblem and swordfighters forever.
Young Link makes it back, but with a moveset completely based on masks. Toon Link got cut (sorry bud, I love ya, but two Link movesets is hella boring and it's clear they won't make Link BotW Link). In this alternate universe Ganondorf gets his tennis ball projectile.
Ike's default is muscular Ike since that's best Ike.
Cut the Pokémon Trainer's Squirtle and Ivysaur to my chagrin, but there are only so many Pokémon you can have before it's excessive.
I think that's it about veterans, now let's talk newcomers. You may notice they're organized by first appearance.
Toad/Captain Toad is one of the most obvious additions in Smash and really needs no explanation. Same with Waluigi. Geno gets in due to massive fan demand, as this is Smash Ultimate dammit. While it may seem hypocritical to exclude Rosalina due to not mattering much and adding Geno who objectively doesn't matter, it's my roster alright?
Also you may have noticed that I put Geno last, well that's because I kinda broke my own rule and included a third-party. But I went with 'no third-party franchises' and included Geno with the loophole that he's a Mario character.
Mach Rider I originally didn't plan to include as I was going to make Takamaru the retro for this game as he had the most support going into 2018, but then I had many a slot and not enough to fill them so he (she?) got in.
Takamaru is the retro. Not much to say. He's cool.
Medusa is an echo of Palutena. I needed an Echo and she's a cool character. Considered Hades who I like more but decided between Falcon, Black Shadow and Ganondorf another fighter like them would be excessive.
Ninten is an echo of Lucas with some moves taken from Mewtwo and I guess an original neutral B (PK Beam) and Final Smash. An echo between Chrom and Ken levels.
Mike Jones I ****ing forgot until the last minute, you can consider him the Wolf or Chrom of this game I guess. Was between cutting Robin and Young Link for him. It was going to be Young Link because I already had Skull Kid and 2 Majora's Mask reps seemed excessive, but I realized that 2 MM reps are less egregious than 2 FE Awakening reps so Robin went. Also considered cutting Geno to abide by my rules and Kamek because he genuinely felt the most expendable, but I took pity on Geno fans and the Yoshi franchise. Not much to say about Mike himself other than I consider him the counterpart to Takamaru and Lip. Also what the **** is that artwork.
Bandanna Dee is obvious and should have been in. Same with Dixie.
Kamek was mainly to give Yoshi a second rep. It's really an important franchise that doesn't get enough credit. After Kamek I don't think it should get a third rep though.
I like Lip. Lip got in because I like her. Also with Doc gone we need a puzzle game rep.
With all the Pokémon that got cut, I figured I should add one that's actually iconic and popular and important and that was Meowth. Feel free to swap him with Eevee, but I feel like Meowth would be more original.
Black Shadow is an echo of Ganondorf I feel. Should have Bull Charge as neutral B, and Falcon's FS, also be hella fast. Included because he's awesome, Japan loves him, more villains, and get F-Zero a second ****ing rep. While typing this I realized I totally forgot Goroh existed and shame on me, but with Takamaru and Lyn he might have been somewhat redundant and also I don't really have unique slots to spare.
Skull Kid gets in due to fan demand and also because Zelda needs one-offs because those are the best characters. Considered Ghirahim and Vaati as well but figured Sheik and Young Link would have the edge with fans due to seniority. With Midna it's the same but also adding that she rocks.
Ray is in. Personally my choice is either a redesign or Mk. III. As for the debate on whether he's Olimar size or Link size, I say a bit shorter than Link.
Saki is in because gunblade and coolness and then I get a new Sin & Punishment or at least a collection. Considered Isa as an echo but nah.
Isaac gets in with an actually decent model and earth attacks and brings Felix as an echo (I know I'm a ****ing loser). Felix is mainly a Dark Samus echo, with tons of different animations (mainly featuring saaaaand and his sweet mask.)
Andy gets in. Sami might be an echo in the future, but for now it's Andy. Real tactics like gimmicky moveset. Kinda like Duck Hunt. I like Duck Hunt.
Lyn gets in and nobody gets to complain because she has it coming for a long while. She has this wicked katana moveset and all of a sudden people love Fire Emblem and stop complaining about it forever. The End.
For a second Wario rep, it was between her and Mona, but in the end I think popularity wins out and it's Ashley. She doesn't get called Ashley and Red because that nomenclature is stupid, Red's just a weapon. We don't call Link 'Link & Master Sword'.
Krystal gets in and Star Fox gets a rep that's not a clone of Fox.
Chorus Kids fulfill the Gematsu prophecy. I'd also take Karate Joe here, but I've really taken a liking to the kids.
Alph actually gets to become an echo because Pikmin 3 is awesome and really changed things around. Olimar gets his Brawl Up-B back, while Alph gets Winged and Rock Pikmin in his moveset. As a sidenote the Koopalings are gone because I hate when alts are a different character. Link's palette swaps are all based on the Champion's Tunic because it's badass (the Tunic of the Wild can be one color).
Octolings are in, and based on Octo Expansion Octolings. They get a lot of new weapons so moveset might differ in a manner that stretches the definitions of what an echo is but still gets called an echo.
Spring Man and Ribbon Girl both get in because ARMS is great. Rex & Pyra also get in because this is literally their only shot and I'm not a monster. Elma stays out because I find her boring and Cross is the real protagonist.
Characters I also considered adding include a Style Savvy rep, King Hippo and I really can't remember others.
Before ending I want to look at series representation
Mario 8 uniques 1 echo
Zelda 7 uniques
Pokémon 6 uniques
Fire Emblem 4 uniques 1 echo
DK 4 uniques
Kirby 4 uniques
Star Fox 4 uniques
Metroid 3 uniques 1 echo
Kid Icarus 2 uniques 2 echos
Mother 2 uniques 1 echo
Yoshi 2 uniques
Wario 2 uniques
Animal Crossing 2 uniques
Xenoblade 2 uniques
F Zero 1 unique 1 echo
Pikmin 1 unique 1 echo
Splatoon 1 unique 1 echo
Golden Sun 1 unique 1 echo
ARMS 1 unique 1 echo
Now I think it could be improved. Pokémon having less than Zelda feels weird, so maybe swap Young Link out for Eevee. Fire Emblem being fourth feels strange, but also representative to its place in Nintendo's stable of franchises and the other franchises' lack of characters. Same with Metroid's low position, it just doesn't have characters. All in all, I think we could do a lot worse, and at least I feel like I fixed Pokémon and Fire Emblem oversaturation.