Instructions
Start the 50CC cup with your character and vehicle of choice. Play through the four races of the Mushroom cup. You need to be among the first three racers in each of the four races to earn a trophy. If you don't make it on one of the races, keep trying and count this round a practice.
Repeat this process with the four races of the Flower cup, again earning a trophy in the cup. When you complete this, the third cup and its three worlds will open up.
Play through the four races of the Lightning cup. Earn a trophy in this cup to unlock the fourth cup, the Lightning cup and its four tracks.
Repeat this process with the Shell and Banana cups to unlock the Leaf cup. Complete the Leaf cup to unlock four more worlds in the Special cup.
Return to main menu, and start a new Grand Prix with 100CC engines. Repeat the process of earning trophies in each of the cups to unlock the new worlds at this difficulty setting.
Complete all of the 32 tracks in 150CC mode and earn trophies in them to open Mirror Class. This gives you the opportunity to play all of the worlds in mirror reverse. In the original mode, when you turned right, you will turn left here. These are all of the worlds you can unlock in this game.