Ok OutKast, begin by guarding Hallow while he calms himself -- if Feu attacks then throw him off the edge with Seismic Toss -- if Gastly attacks, blow him back with a psychic. If neither, set up a calm mind of your own. Then, I want you to hit Gastly with a shadow ball, hopefully lowering his sp. def for Hallow's attack and also so that he cant interfere with feu and next vice versa by slamming feu with a brick break!

Calm Mind ~ Shadow Ball ~ Brick Break

Subs: Seismic Toss ~ Psychic