Super Mario Kart Cheats

To get ghost racer simply choose any track and don't touch the sides, and race the ghost rider

Enter time trials and hover the cursor beside Mushroom cup then press L,R,L,R,L,L,R,R,A. Special cup will then appear below star cup

To erase all ghost data press L,R,Y,A and this will take you to reset mode

This is quite a cool secret, all you do is hold Y and then press A on the character selection screen
Anotehr way is to highlight the character you want to be and press A,B,X,Y at the same time

Go to Time Trial mode, pick player, and start a race. Finish the race and get 1st place for your time. Press Retry and you'll get to race yourself!

Go to Time Trial, put the cursor on Mushroom Cup and press: L,R,L,R,L,L,R,R,A. If you haven't unlocked Special Cup already, it'll be available now.