How do you level up Master Form quickly in Kingdom Hearts 2

Go to Land of the Dragons. Start from the beginning of the world, and activate Master Form. vanquish every Heartless that you see, while moving onward towards the Emperor's Castle. Once you are finished, go back and repeat. This is the strategy that I used, and it was quick and easy. Remember that you gain 1 exp. for every small orb, and 3 exp. for every big orb obtained while in Master Form. Good luck!