Things You'll Need
Instructions
Installing the Homebrew Channel
Load up a SD card on your computer. Download the Bannerbomb exploit abd6a_v200.zip and the HackMii installer onto the SD card (see Resource 2). Go to the HackMii file and rename the program "installer.elf" as "boot.elf".
Turn on your Wii with the SD card inside. Go to the "SD Card Menu" and click "Yes" on the pop-up that appears. Press "1" on your Wii remote to continue.
Click on "Install the Homebrew Channel." Wait for the installation to automatically complete. Do not install any additional files. Exit and delete the "boot.elf" file when completion.
Installing Brawl Minus
Create a folder called "apps" on the SD card. Then look in the list of existing folders for an .exe file and rename it to boot.elf (or boot.dol if it is a .dol file). This is needed to run Brawl Minus.
Install Brawl Minus from its official download site (see Resource 1). Copy all files onto the SD card.
Open the Homebrew Channel and start up Gecko OS 1.9.3.1 to run Brawl Minus.