Waluigi does not count as an actual character in my book. EVAR.
He was made up just for Super Mario Tennis. Then got added in a few other games as a cameo role. Just like Daisy.
So I guess I'll stick with Wario. Because he had games for the Gameboy. Not Gameboy Color, mind you. The Gameboy. Which was the size of a small brick, had a screen which was only 4x4 and ate batteries faster than you could buy them. Good times.