Seriously, the ability to toggle by stage is already there. Assist Trophies themselves aren't even always on, and even when they are, every assist is not always available as it is on a stage by stage basis. Simply turning off one on a fighter basis shouldn't be too hard. Yeah, they'd hopefully make a new model, but that's no more work than the others as pointed out (though, I'm not entirely convinced they didn't just use Chrom's FS model for his fighter explaining the lack of quality). They may not even reuse much if anything from the assist given how radically different Dark Samus was as an assist (and likely a better representation). And, yeah, given the ludicrous amount of work they put into Joker, Heroes, and Terry, it shouldn't be out of the ballpark. Granted, maybe they don't care as much because its first party, but the assist shouldn't be the end. We know they can turn off assists, so why not this one?