I find the WiiChuck garbage to be the worst controller I've ever used, and seeing that.... Tablet thing killed my Wii U interest. I regret getting a Wii, it has too many games that are marred by being forced to use that terrible contraption.
wiichuk is actually better for smash than the classic controller in my experience, the sticks on the classic controller are awful, basically third party quality, and are not conducive to the fine movements you usually need. results seem to correlate this, there are a few top players that use the wiichuk, I can only think of one that uses the classic controller
gamecube controller is still by far the best though, it's too bad nintendo is turning their backs on it already instead of recognizing that they had a great thing going