Two healers and a character that can reduce burst damage taken (Roland, Joan of Arc, Gaia, etc) is all you need to win this fight at lower power. As long as you have some way to nullify the damage from the Garuda ultimate, winning isn't too bad even at 20k or less stats.

I was able to do it with 1 healer and Mordred and no damage reduction at 23k stats, though it cut pretty close.