This has only happened because there was literally nothing else fitting at that point. There's no "gunner"-like characters, hence the Capcom MegaMan costumes being randomly placed.
Rocket Grunt literally fits no one, as nobody are a generic class character other than Hero, and that was pretty hard company specific.
Lloyd isn't back for the same reasons. You could argue Byleth at most would've fit, but otherwise, the rest have some pretty big specifics.
Chun-Li actually fits being with someone like Min Min or Terry, being Fighting Game characters. Even with barely any similarities to Min Min, that would've been logical.
There is logic, but the grab bag costumes are actually a lot more rare than common. So... this isn't a good reason for it.