If I were to add Hatsune Miku to a fighting game, I'd probably give her a unique mechanic that rewards her with a crotchet or quaver every time she lands a just frame (to replicate the concept of "perfect" inputs in rhythm games) and buffs her moves every time you fill up a bar or triplet.
You could probably build an entire game around a system like this if you wanted it to put special emphasis onto tight execution without going down the route of stupid inputs like the pretzel motion, but I'm not a game dev or even particularly good at fighting games, so there's probably more to consider when implementing something like this.