How do you get the Leaf Cup?

To get the Leaf Cup on Mario Kart you have to always play Mario with 50cc and the B-dasher kart on the Mushroom Cup. Soon one of your question marks will evolve into the Leaf Cup. But if you want it, you have to get the Mushroom trophy every time. When you win the cup, when you press A to finish it, you will find some writing saying you have got the Leaf Cup!