I've been thinking for some time about how to respond to the beginning of this post or dream1ng's post, and I think it'd be good for me to amend some of the stuff I said.
I think the gist of it is like.....if you asked someone to make a SEGA roster that balances both regions' appeal, it could totally be done. Provided they know their stuff, they could probably strike a good balance. Theoretically it's possible. But I think to me the big thing is.....it still feels weird for me to imagine how that approach would actually be taken were a game like this to officially happen, because we've no real precedent for how that would happen. As I've mentioned, we have so far never seen an official SEGA-adjacent thing that tries to reconcile both perspectives - the usual tradition has been stuff fully geared towards one crowd or another. The closest we've come is maybe PxZ2, but as I've mentioned, there wasn't much space for us to really see the full extent of that potential. So it still feels like this weird thing to think about, it still feels like a big question mark to see how it would actually be done. It's not a matter of "can it be done", because it can, it's moreso that we have no clue how an actual official dev team would handle this. That might seem like I'm splitting hairs but I do think that distinction can be important to make - a fan approach and an official approach can be very different - and I'm not even trying to gatekeep anyone's attempts by claiming they're "not accurate to how it would be done", these are moreso just.....musings. Stray thoughts I have sometimes. I'm moreso just.....curious to see how actual devs would handle this, considering how little precedent we really have - like, which characters do they prioritize? which characters would they consider on either side? Who would be "too Japanese" or "too western" to be considered? What concessions would have to be made? Again, I'm not trying to invalidate anyone who tries, I moreso just.....wonder. It's curiosity more than anything else.
It's funny you mention the Capcom vs. games' attempts in this regard, cause that was exactly what I was thinking about with the whole hypothetical of "JP devs trying to make a roster with international appeal". Like, that to me is the other big "reference point" I've been thinking about throughout this conversation in terms of that approach being taken and how it would be applied to SEGA. The things with them explicitly choosing/cutting characters based on worldwide appeal have been the go-to example in my head that have made me wonder how this would actually be done as opposed to my weeb-ass rosters. So good on you, because I've been thinking about that too.
On the last point, you mention how a character being fun and interesting could be able to overpower any regional blindspots, but I actually think that's precisely why the balanced approach can be so interesting. We think about it in terms of having characters that appeal to each region, but we can flip that to mean we also have characters less familiar to each region and that can serve as cool learning experiences. Like, think about it from the perspective of your average Western fan - you pick up the game, you recognize the likes of Sonic and Yakuza, and if you're older you'll probably know Streets of Rage, Golden Axe, Jet Set Radio, etc......but who's Sakura? Oh, she looks kind of cool actually. What's this giant beetle thing popping out as one of my assists? I wanna know what that's from. This probably applies less to Japanese fans because I can't imagine they'd add anyone who leans too western, but that's the cool thing about this approach, and about crossovers in general, getting pulled in with the faces you know and then seeing all this other stuff you haven't heard of before.
This is gonna sound deranged, but I think a SEGA thing that could actually serve as a pretty good basis for a thing like this is actually.....the SEGA logo that plays before the Sonic movies. Like, the variety of the stuff shown and some of the deep cuts they make are actually kind of admirable, with a good mix of known faces and more obscure stuff. Like, it has a bunch of the well-known-in-the-West staples that fans can latch onto, but it also has plenty of room for the cool weird distinctly Japanese cuts that really add some flavor. Yes, you have Sonic, Monkey Ball, Jet Set Radio, NiGHTS, Streets of Rage.....but then also Sakura Wars, Dynamite Cop, Roommania, 7th Dragon, Guardian Heroes and the like. It feels like a really nice and well-rounded mix of stuff, and I think that might be the ideal approach for a game like this.
Thinking it over, I kind of want to try my hand at a "regionally-balanced" roster now. Seems like it'd be a fun exercise