Download this template and put it in the "Riivolution" folder in your SD card.
Then put any file with the correct original name in there. It's kinda like the "My Stuff" folder in Mario Kart Wii, except everything goes in there. I made the XML myself
Took me a while because I got confused.
Download cool Brawl mods:
Assist Trophies, Characters, and Stages original file names:
Music (BRSTM) original file names: