Does anyone have any suggestions on how to defeat the Gurg on Gen 4? I CAN'T DEFEAT HIM!!! scream crying

My Primary are Ellis(LVL 65), Zerva (LVL 69), Duran (LVL 64), Silvi (LVL 62), Alberti (LVL 60), and Reverie(LVL 59).

I'm playing Easy Mode.