Super Smash Bros. Brawl is a Wii game.
What he means are not GamePad controls, but the ability to play Super Smash Bros. Brawl with the Nintendo GameCube controller. Since it's a Wii game, if this is possible, it could be for more Wii games. Perhaps there is a way to unlock the USB ports in Wii mode and the Wii U thinking there's a GameCube controller attached to it?