Also I realise I had something typed up to talk about this but I forgot to post it.
I would say between Dark Souls and Elden Ring, the Tarnished (Elden Ring protagonist) probably makes more sense than the Chosen Undead (Dark Souls 1 protagonist), Elden Ring was such a massive dominating success that catapulted FromSoft's library beyond just the gaming community. I think it's tempting to favour Dark Souls for the legacy and history behind that name, and I think that definitely makes sense, but Elden Ring's sheer popularity makes me favour it. Part of the theme of Dark Souls is that ultimately the choice you make about linking the fire doesn't matter, and the world forgets about you no matter what. Dark Souls is a story about its world, less so about the Chosen Undead, who's destined to be irrelevant and forgotten both within the game itself and especially in the sequels. Elden Ring is also very much a story about its world, but I would say it's much more about the Tarnished than Dark Souls is about the Chosen Undead, the player character is given more agency and narrative function, and is treated that way in marketing in a way the Dark Souls protagonists aren't. It kind of lines up with how Elden Ring's story is more about "the world got ****ed up due to the actions of this one person" while Dark Souls is more about "the world got ****ed up due to the cycle of life and power", drastically oversimplifying ofc.
I don't think either would struggle for a moveset either, but Elden Ring is such a massive game that you could give the Tarnished 10 distinct movesets with zero overlap without having to make up any moves, I think it'd be easier to veer away from a sword and shield + spells build that the Chosen Undead might gravitate too while still feeling like a Soulsborne protagonist.
Imo, the ideal way to handle Elden Ring/Dark Souls in Smash within reason (ie not just adding playable characters for both, though it is probably big enough to warrant two characters) would be like:
- Tarnished playable character
- Stage revolving around the Erdtree
- An Anor Londo stage, with variants for both Dark Souls and Dark Souls 3 depending on the music playing
- A Dark Souls boss for the singleplayer. There's a lot of good options, and I think if it actually happened for whatever reason it would probably be Ornstein and Smough, but I would personally go with Slave Knight Gael
- Solaire assist trophy
And of course, Bloodborne PC unveiled within game when you beat classic mode at 9.9 difficulty without taking damage while wearing a blindfold.