Mixing and matching just the best moves from the three current Mii Fighters would already be really overpowered. So my specials are Grenade Launcher and the bomb from the gunner, Helicopter Kick from the Brawler, and probably the spinning sword move for recovery from Swordfighter who needs side special otherwise? I'm going to have Swordfighter's tilts, Brawler's jab and dash attack, Gunner's smashes, Gunner's fair, Brawler's nair and bair, Swordfighter's uair and dair, Brawler's throws... Do I get to keep Brawler's mobility parameters too? This character is really overpowered, probably the best character in Smash 4. You're letting me make literally every one of my moves good and letting me have multiple character definingly powerful options that basically allow me to be all of the best things about Villager and ZSS at the same time except add on a good grab game and a few sword normals for good measure.
How Smash handled the current customization of Mii Fighters was basically to severely undertune almost everything which is why Swordfighter and Gunner are mostly just bad, but even then, with so many options something fell through the cracks and Brawler is a fairly good and mostly dumb character mostly because Helicopter Kick is just a bonkers move ("substantially better version of Boost Kick" is a hilarious move concept). Smash Ultimate it seems is going to be more careful with the tuning, but certainly massively magnifying the options would be going the wrong way here. The ideal is for the three Mii Fighter archetypes to be fully integrated as normal characters so we can actually use them. For most practical purposes, they might as well not even be in Smash 4 (they're effectively or actually banned at almost all tournaments, and online players can pick them either); that's the angle I think about when I think where I want to see these characters go...
