Okay, Ralts, we've got a lot of stuff headed our way, so first put up a Light Screen to dampen all of that. Then, if her combination attack keeps her from attacking for a while after it, I want you to relax while she's not attacking, and finish with a Fire Punch. Otherwise, switch it around and Fire Punch before relaxing while she doesn't attack.

Light Screen ~^~ relax / Fire Punch ~^~ Fire Punch / relax