To play as T.T., you must race each course in the Time Trial mode until T.T. comes out to challenge you, and he won't appear until the pre-programmed track record in a particular track is beaten by a large margin. When he challenges you, you must defeat him in a race on that course. Once you do beat him, a small T.T. symbol will appear on that particular track. You must beat him on all tracks to get him as a playable character.