First up, every active 1st party series with a character should retain at least one character. To my knowledge, these are Super Mario, Donkey Kong, The Legend of Zelda, Metroid, Kirby, Pokémon, F-Zero, Fire Emblem, Game & Watch (kind of), WarioWare, Pikmin, Animal Crossing, Xenoblade Chronicles, Splatoon, and potentially, ARMS. Assuming we pick the main rep for each, this gives us:
A few notes:
- Game & Watch is only technically active through the Super Mario Bros. and The Legend of Zelda collector's items. It could be argued these are more for Mario and Link, but it does use the Game & Watch brand, so I'll allow it.
- Though their casts rotate, Marth and Shulk definitely need to be here, as they are both the most well known characters from their franchises, and played a major role in their last game's stories.
- ARMS's future is tenuous, but it hasn't been long enough to declare it dead.
Step two is to add in the major veterans within these franchises:
Step 2.5 is dealing with the rotating casts:
- Fire Emblem I think is the easiest to handle since we can directly respond to the complaints by prioritizing the more unique characters while trying to keep the representation spread throughout the series, which gives us and. I'm also throwing in Schrodinger's since I think 4 full Fire Emblem characters is a good number, but if we're adding a newcomer be it Lyn or Alear, I think they should take priority. If we're not though, he should probably be here.
- Pokémon is a headache, as you can make a good argument for all of them to be here, but we can't keep 'em all. The representation has also been balanced horribly with 6 Gen 1 picks, and one from Gen 2, 4, 6, and 7. I'm giving up on the idea of this series truncating down to 6 slots including the newcomer in favor of just having 6 "slots" total. The editions here will be (), , , and either or . This gives us the series protagonist, and a major Pokémon from Gen 4, and either Gen 6 or 7.
- I think Xenoblade Chronicles is in a bit of a wonky position, as it hasn't quite instantiated it's big faces other than Shulk, but I'd say it's gained the right to fill out its roster, so keeping / is perfectly fine +- a newcomer. I'd hesitate to keep them if we're getting two characters though. If we're getting none, then they probably should stay.
That leaves us with Super Smash Bros. staples. The kind that, if gone, will be sorely missed by the vast majority of fans. Most of them get in on above criteria, so that just leaves us with a few difficult picks. The problem with picking off of this criteria is that there are a ton of characters who could fit this criteria, and when you try to avoid keeping literally everyone this way, you kind of just bias your way through it.
I can't really have my finger on the pulse of all smash fans everywhere, so this is about the best I can do.
In total, that's 44-45 characters, which would set the roster at 59-60 characters if you added 15 newcomers, which could easily mean that I'd need to downsize from here, probably by about 5-8 characters depending on what's feasible and the desired newcomer roster. Also I just realized that I completely forgot about 3rd party characters. In conclusion: I don't envy Sakurai.