If you are looking to preserve games, the best method is to dump your own discs using a Wii console with homebrew installed (using software like CleanRip). This gives you a pristine 1:1 ISO file. You can then convert that ISO into whatever format (WBFS or RVZ) suits your playing needs.
Downloading ROMs of copyrighted games that you do not own is illegal in most jurisdictions. Culturally, the emulation community encourages users to create digital backups of their own physical discs using a homebrew-enabled Wii and a tool like CleanRip .
Originally developed by Waninkoko, WBFS is a disc image format specifically designed to store Wii game backups on external storage like SD cards or USB drives.
Do not google "free wii roms download." The internet is full of malware and fake "Wii ROM generators." Instead, use dedicated emulation subreddits (/r/ROMs) and look for the "No-Intro" or "Redump" collections via torrents or Internet Archive. Always verify your downloads with a virus scanner.