It's been a while since I beat him, but... I was like level 50 the first time.
First things first, how many djinn do you have? In order for your characters to properly defend against his attacks, you want to have at least 4 set to any given character. This allows you access to classes with better psynergy, in particular, Wish/Healing Gust, Revive, and Impact/Weapon Grace. Protect and Resist are also helpful, but not by much because some attacks ignore defenses I think.
Always have at least one party member who has Revive, preferably Matthew. In fact, his djinn should always be set, not standby, so you can use him to attack more proficiently as well. Use Impact/Weapon Grace on him to boost his attack more.
Also have a healer who can heal the entire party in one turn. If your chosen healer is slow, use the healing spell before your health gets below half because you want to keep your HP up as high as possible. CC will attack, then your healer will heal afterwards. If your healer is faster, heal the party after their HP drops below half instead.
Keeping djinn set on your healer will increase the amount you heal per cast if the healing spell is the same element as that character's djinn. This is far more effective than healing items.
CC will use an attack that drains your djinn, putting them in recovery. This is where it gets tricky. When that happens, I recommend switching out your weakest non-healing party member to a character that has a djinn that can use a defensive wall (Chasm, Shell). This gives you a free turn to recover djinn while taking little damage. If that character also has a djinn that can speed up djinn recovery or block an enemies movement once, use those too. Once you're back to 4 set djinn, summon anything you have, and you can continue attacking and healing. If your attacker can hit several hundreds of damage per turn, it shouldn't take too long.
I was able to beat him on my first try like this.