This battle is fairly simple, but if you let Luxord get an edge over you he could quickly kill you. Don't leave yourself open, keep attacking.
When it comes to a reaction command (in which he says "Do you know the rules") wait for the card behind you to raise up and reveal a certain symbol. Immediately press it, and it should stun Luxord and release some health balls.
Whenever he is not attacking always go after him. He may turn you into a card or die. In either form, use O to attack Luxord. It will drain the drive bar more quickly, and once it is emptied, you will turn back to normal form.
This is the basic strategy, until he comes to critical, then the screen will center on Luxord, and a bunch of cards will fly out. He will duel wield two cards, and attempt to hurt you. He will also fling cards at you. Simply run away until he stops.
He will then make a huge barrier surrounding both of you with cards. Then the same reaction command will pop up. Do the same thing as before, and it will show Sora throw some cards at Luxord and deal a lot of damage.
All you have to do now is hit the finishing blow, and you will have beaten him.
Hope that helps.