Do I need to own the disc? I have an iso loaded for my wii, want to make sure I have everything set up correctly before starting races with anyone.

if your using a iso from a usb use dios mios 10 and for sd iso loading use dios mios 11 lite. Those are the only things legal for iso loading

my bad 2.10 and 2.11 lite

Generally, USB/SD loading is not allowed for most games, but this game is an exception. If you want to know what to use however, then for USB loading it's Dios Mios 2.11, and for SD card loading it's Dios Mios 2.10 Lite (you have to install the wads with a wad installation program)

the disc is like, $15. just get the disc