How do I defeat Marluxia First Form?

Well I know this is pretty lame but I just used a full deck of 0's and broke every card that he tried to use. Add in a couple Heal cards just in case. If you have a Neoshadow enemy card, use that to drain his HP faster. I was only lvl. 70-something, with almost two full health bars and 1000 CP.

This worked for his second form, too, but it took FOREVER. Anyway, hope this helped.

Hahahahaha I was lvl 70, full health and like 1000 CP... Have like 4 0's if you don't want to take 3 hours...
Have 9's and 8's within 10-20 less you have more, but cards lower then 7 are a wate cept for a 0 so don't watse your CP.
Have as many high level clouds, I had 5 6lvl clouds and an 8... Have 4-5 high cures, I had 3 lvl 8, a lvl 9 and a lvl 0... I murdered Marluxia with this deck. Skip past the first 4 0's, then just rape him with the 9's and 8's..., when he does a big attack like the sweep with the scythe, or the balls of floers use a 0. NEVER stack the 0's. When you get down to the green bar go ahead and use a cure by itself. Never stack cures less you have to, taht being your at low green.

Okay it was my friends lvl, I worked on the last 5 or so levels and so lol. But remember the game isnt just about the cards, you could still dodge every attack your opponent throws if your a good player, takes time to learn his moves but by half his health down he didnt hit me

Fire are his weakness

And get a lot of zeros in the backside of your deck