Is there any other way to beat Riku the last time when he has 3 health..

There are cheat codes for this game on both an AR and Gameshark, if that is what you are asking.But if you use them, do it at YOUR OWN RISK! I used like 5 cheats and it screwed my game up terribly.So I started a new file and beat the game!

Anyways, the best way is to have your CP at about as high as it can go.(It goes up to 1900)This will help you in other fights later on.So add about 5-10 zero cards in the front.These zero will destroy his sleights, like Dark Aura.Then have lots and lots of 9 and 8 and 7 cards backing up the zero cards.And taking up the rear and saving your ass a lot have a bunch of Cure cards.The best enemy cards you could have in this deck are Oogie Boogie, Search Ghost, and (for the Cure cards)Creeper Plant.

NOTE:When the fight starts, scroll to your first 9 card to attack hiom with.But when you see him start his deadly Dark Aura press the L shoulder button and use that zero card.

Also before your fight try to open the Key To Rewards door in either Olympus or Traverse Town to get the Metal Chocobo or the Lionheart key cards.

This time, some things have changed... First, he seems to have a lot more HP, plus now he has a new special attack, which "only" turns out being one
of the best ones in this game... So, I guess you will need some more advices this time... Be sure to put lots of 7, 8 and 9 keyblade cards on your deck, some healing cards (3 or 4...), many Cloud cards (5 or 6, I
would say) and finally some cards with value 0, all in this particular order.

Now, use the same technique that you used against him before, I mean, strike with combos of 3 Cloud cards, lots and lots of strikes with your best keyblades and heal when necessary, I mean, whenever your health probs above its its medium value.

Also, be sure to use your cards with value 0 to stop Riku's best move, which turns the entire screen black and causes you a lot of damage. Apart from this move and his increased health bar, just be sure to beat him as you did in the previous fights against
him...