The adapter should treat the GameCube controller as a standard classic controller which has analog triggers but rumble will never work due to the design of the Wii Remote. I do believe there is an option in Nintendont to allow the Wii Remote to rumble.I'm not so certain. It looks like it plugs into the Wii Controller, which only officially supports the Classic Controller and Classic Controller Pro. Even if it somehow passes analog trigger commands to the console, connecting a NGC Controller through the Wii remote is rare enough the nintendon't may not be programmed to expect that.
But really that's just my common sense assumption based on what I know. It's possible that it'll somehow work anyways.
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Nintendont will never work in Wii U mode due to hardware differences to vWii mode.Game Cube on Wii U ? FIX94 does :v