BeatsByFlandre
I missed the Subspace Emissary from Brawl, and felt it did some things right although also other things wrong, but mostly right. So I imagined, what if Smash Ultimate had a story mode like SSE as say, an exclusive Switch 2 update where you can also unlock all the DLC fighters from playing? You still have the starting 8 original fighters of course and they will appear in the mode too for story purposes and completeness. In the end, I came up with a mode that would utilize enemies and mechanics from the franchises of the characters represented. It would be a set of 11 short, disconnected stories I call chapter (though you'd start with 3 to choose from and doing it unlocks the rest) with 7 levels each, and you'd unlock a different fighter after each level who did something significant by the end of it. There would be no dialogue like SSE, so I'll just be describing the cutscenes, levels and any unique mechanics they may have. Disclaimer: I'm familiar with most franchises in Smash but not all of them so apologies for any inaccuracy and/or guesswork for the ones I am unfamiliar with.