We do not condone piracy. You should only create a WBFS file from a physical copy of Mario Sports Mix that you own. Downloading pre-made WBFS files from torrent sites may be illegal in your jurisdiction.
Have a problem with your Mario Sports Mix WBFS not booting? Leave a comment below (or check the GBAtemp forums for specific cIOS slots).
The game focuses on arcade-style gameplay where traditional rules are secondary to Mushroom Kingdom antics. Basketball:
Open Wii Backup Manager and set your external hard drive as "Drive 1."