I never made a blanket statement saying all characters from popular games don't have moveset potential. No idea where you read that.
Fact is, dismissing a character based on how many copies their game sold or whether or not their game was liked is a really crappy way to speculate. Fates could've bombed and been the most controversial game in the franchise, but that wouldn't take away from Corrin and his ability to transform into a dragon. Same thing applies to other games where I see the "shouldn't get in because their game sucks" argument used. Doesn't matter if you loved XC2 or not. Rex and the driver mechanic has a lot of potential either way. Paper Mario? Sure, I can admit that I don't like the newer games as much as the older ones, but does that mean I don't see any potential in the Paper Mario who exists in SS, CS, and OK? Not at all.
There's a lot of great characters who probably don't get the recognition they deserve, and that's largely because people are focusing too hard on the game and not the character.
Also, when did I ever say PP never had moveset potential? I'm one of the few people in this thread who defends its inclusion because there's so very few characters capable of doing half the stuff it does.
I can dislike characters because I simply don't like them. If they're from a game I don't like, then I won't be thrilled that a game I don't like got included instead of one I do like. If I don't like how a character could work in Smash, them officially getting in won't make me change my mind. I know how Rex could work as I've seen many fans suggest the same ideas, but I don't find those ideas fun, not worthy of my precious 5.99. Would it be unique? Absolutely, but having to wait for Pyra and/or Mythra catch up with Rex to be able to fight effectively doesn't sound fun to me at all. If you can't dislike a character because you don't like them, don't like their game or don't like how they'd play in Smash, what good reason is there for someone to dislike a character? Movesets are important but the characters they're attached to are just as, if not, more important.
Not really, most people are more open to smaller franchises, because they like those games and characters.
I used PP specifically because it's one of my favourite examples of making a moveset out of nothing. Sakurai has made fully fledged fighters out of a literal toy, a yoga instructor, a dog that only ever laughs at you and more, so saying characters from highly beloved franchises don't have moveset potential is dishonest, unimaginative and hypocritical. Your whole post read as "You can't dislike characters I want, that's gatekeeping, I'm allowed to dislike characters you might want though, they don't have moveset potential". There's also examples of people not liking the movesets given to characters like say, Shulk, who plays drastically different from his source game, and not because it's a different genre. I just don't get how movesets are the end all be all but only for 'smaller' franchises like Mario and Pokemon whereas some large franchises suddenly don't have moveset potential because you said so without any examples because for what I can only assume is because you knew fans would go "uh no you can easily make a moveset from a character from Halo/RE/Tomb Raider/Madden Football, etc."