I'm not sure how it works technically under the hood. I got Paper Mario as a ".wad" file instead of the normal .iso that you see for GC/Wii/WiiU games, and Dolphin was able to load the .wad file.
Ah, you are probably right, my mistake. Unfortunately I can't edit my original comment now. I was under the impression it was a Wii U file since I downloaded it from a reddit link I found that said it was a Wii U Virtual Console title. But, doing some research it was also released for the original Wii VC at some point, so it's likely that's where the file came from.
My understanding is that `wad`s are specifically for the Wii (and Google seems to back me up on that), so regardless of where they got it from the fact that it was a `wad` means they were playing the Wii version. If it was an actual Wii U version it would be some other format.
