I got Zodiark before the best magics (eg Scathe, Flare) were available.

Zodiark casts paling when his health reaches 20% so right before that I did a quickening and got off a decent chunk of his health. Then I gave all my characters either mirror mail or ruby ring so they all had reflect, and I cast Bio off of them which hit Zodiark 3x. I also had one of my guys casting reverse and decoy so that the other party members weren't affected by his scathe bombardment. Finally, I made sure that my characters all had shell on them to decrease the chances of Darkja from instant KO'ing my guys (if there wasn't time to cast shell I just gave them shell shields).

It definitely would have been easier to wait till after Pharos, but I really wanted to get Zodiark as soon as I could get him.