What platform do I put if I run it on Wii not VC?

How do you run it on Wii but not on VC?

Im assuming they mean using the Gamecube disc but playing on a Wii.

Platform is the version of the game you are playing on. If you are playing the Gamecube Collector's Edition then you would use Gamecube even if you are playing it on the Wii through it's gamecube emulator.