Change the XX in the FitLucarioXX.pac and FitLucarioXX.pcs files to the numbers that correspond with the slot you want to place the costume over.

PROJECT M:
00 - Default
01 - Red
02 - Green
04 - Dark Gray
05 - White
06 - Shiny
07 - White Gi
08 - Gray Gi

BRAWL:
00 - Default
01 - Red
02 - Green
04 - Teal
05 - White