Basically, what I'm trying to do is have each individual costume have a different final smash. I heard this was possible with Brawlex.
For example, have Wario's blue costume use a blue Wario Man skin, while the rest all use regular Wario Man.
I don't know if this little piece of information can help you at all, but Project M had this happen with Giga Bowser.
Ty
Use the Brawlex Config Utility to set the "Final" field to multiple for a fighter##.dat
Then Fit*## will load its final smash from Fit*Final##
You'll need to have a final smash file for each costume though.
For example, when Ganon's "final" field is set to multiple, FitGanon00 will load its final smash from FitGanonFinal00