nintendo thought it would be funny to not let you be able to do that! there are some methods though like brainslug, buying a gamecube to wii remote adapter, or simply playing gamecube games on the vwii with nintendon't since you can just use the gc to usb adapter on your wii u

Early Wii models had a port on the side, if you don't see it, your game won't play, but just use emulation on Wii U if you can, or smth, I use a 2DS, not a Wii or Wii U