(1) Check if your version of Brawl is NTSC-U and 7.92 GB.
(2) Extract Smash Universe to SD card.
(3) Copy RSBE01.gct from Smash Universe to "codes" folder(s) on SD card:
SD:\codes
SD:\wiiflow\codes\gct
SD:\usb-loader\codes
(4) Set Loader Ocarina to ON.
(5) Set HookType to AXnextFrame or VBI.
Because of the size of the mod, there will be a black loading screen for about 2 minutes before the opening movie and the character select screen will be laggy.
Or, try older Brawl mods by using BrawlBuilder to create a modded Brawl ISO with Project M: Patt or Fully Dressed editions.