You need the homebrew channel on your vwii and USB Loader gx or wiiflow. Wiiflow can boot .wbfs game files from an sd card. USB Loader gx can boot .iso files from a usb, although I'm not sure it works if it's formatted for Wii U, plus it's really unstable in my opinion

I think you can also use something like UWUVCI (on computer) to convert Wii backups to installable Wii U menu files, and then use WUP Installer GX2 to install the backups. I'm on Aroma CFW so the method may vary but I recommend looking for up to date guides on this sort of stuff.

just put in the disc lmao