Gotta love the Smash community and it's double standards.
"That character is a dumb fit for Smash, they're old, irrelevant, and dead! My character though? They're perfect for Smash, who cares if they're old, irrelevant, and dead?"
To answer the questions above. There are some Japanese characters I'd like to see playable and there are some Western characters that I'd like to see playable. I don't like choosing a character based off their country of origin and I prefer to treat a character based on their merits and how good their game is. I never enjoyed the argument that a character's inclusion depends on their country of origin. I've seen many people, including some users on this site, who claimed Western owned characters would never get in Smash just because they're Western and not Japanese. Not only is this argument narrow minded, but we saw that it was full of bogus after Banjo got in. So how did some of these people react to Banjo's inclusion? They moved the goalpost and claimed only western owned characters that have ties to Nintendo can get in Smash. It's getting silly at this point and using this argument requires Olympic levels of mental gymnastics. Let's be smart folks, arbitrary rules that don't have a strong argument are never healthy for discussion.
As for GTA characters I'd want to see.... It's probably gonna be CJ. San Andreas is my favorite GTA game and CJ has the biggest potential compared to the rest of the cast. San Andreas was jam packed full of content, with items that never saw the light of day again like Jetpacks and spray cans.