I'm not gonna repost the whole post again but I think pic related spells out the problem with the roster well enough compared to Smash

I don't mean to say Nintendo's the only one that cracked the solution to this because Capcom did the same thing.
Have strong, internetionally popular franchises of critical acclaim and sales made by mostly the same people and you have enough healthy overlap to create a core fanbase for the company('s games as a whole).
I've seen people wonder what a SEGA Smash Bros would look like but honestly given the industry politics at the time between SEGA of America and SEGA of Japan, I don't think a SEGA Smash Bros roster (had it released back when SEGA was still producing consoles) would even work given how the former would cockblock certain Japanese games from releasing and the latter doesn't like to acknowledge the former's first party offerings unless it's for some collection.
Anyways, another worth noting is how PlayStation All-Stars boxart varies from location.
Kratos in the middle of the American release, Drake for Europe, and Japan is an absolute clusterfuck of all the various renders just slapped on together.
Keep this in mind, it's gonna be important.