Freya should jump or perhaps use Reis's Wind. Eiko should heal with Cura, although she may be able to get in a quick summon attack with Fenrir. If the player has proceeded far enough in the chocobo sidequest Eiko could also use Holy. Dagger should focus on healing or attacking with her eidolons, although her unreliability at this time can make her a hindrance.
Using a Tent or two on Meltigemini at the beginning of the battle can prove useful, as it may spontaneously inflict Poison, Blind and Silence.