Instructions
Start racing in the "Flower Cup." Complete every race in the "Flower Cup and place at least third in the overall standings of that cup. Once you have won at least third place, you will open up the "Star Cup."
Race on the recently unlocked "Star Cup." Place at least third place in the overall standings of the "Star Cup" to unlock the "Special Cup."
Select the "Banana Cup" and begin racing. Place at least third place in the overall standings for the cup. Once you have completed the "Banana Cup," begin racing in the "Shell Cup." Place at least third in the overall standings for the "Shell Cup" to unlock the "Leaf Cup."
Race in the "Leaf Cup" and place third place or greater in the overall standings of the "Leaf Cup." Once accomplished, the "Lightning Cup" will be unlocked.