Emulators are not illegal, as they are simply re-made version of consoles. It is a completely re-made version of the original Wii and GameCube consoles. This step is only required if you want to use real wiimotes to play wii games on your Mac. The Dolphin app is an emulator for both Gamecube and Wii.
8 What happens if you put a Wii game in your computer?.3 Do you need a Wii remote for dolphin emulator?.1 How do I play Wii games on dolphin Mac?.