Megaboom

Okay update. I somehow got lucky and won. lot's of lucky crits and enemy misses.

So I'm currently at the battle with Madelis at the prison. I think I'm stuck because I'm unable to go back and grind or change my team and her houndoom keeps wiping my whole team. I saved in the room it's self. My team is a Level 37 Meowstic, a 39 Talonflame, a level 38 Froslass, a Level 40 Banette, a level 40 Decidueye, and a level 39 Nidorino. I'm playing on casual mode. Any help would be nice