Okay, the files in ui/result/font are all modeled letters. I know Smash WiiU has 660 different characters in the various unicode planes, so it essentially uses the different models to build the character name letter-by-letter, which is why it handles all the goofy Mii Fighter names with ease.
I'm pretty sure the other ones, such as CSP names, are just textures. I don't know if you'd want to edit those, or what the format might be, so I can't really be too sure, outside the guess based on how they did Brawl.