Kid's equipment, Clear Light, should be unequipped to win against the Goddess. Since she uses Black element against you, that's why he dies so fast...and why checking your equipment and menu is beneficial
Strategy #1
Use Tyrfling at the start of the battle.
Defend and Keep throwing Ruby Roses at the goddess/Use Little Meteor
Keep Making Kid use chocolate nuggets on himself
If low on HP Defend then Serenade Bell. This will make Sairen always go first.
Once Kid's TP is 100 use Akasha.
Phantasmagoria should activate around Turn 5/6 when you used it.
Boss would be dead by Turn 5 if you did it right.
If you want a video: