ImDisk

ImDisk is a tool that allows the user to mount, create, and edit image files for hard drives, CD-ROMs, and other physical media. In the context of SSBB modding, it allows the user to create and edit sd.raw files which is where all the edited game files are stored. This makes it functionally mandatory to use unless you prefer VSDSync instead.

ImDisk can be downloaded from here: https://sourceforge.net/projects/imdisk-toolkit/

Relevant Guides

• SD.raw Basics