Lol.I'm glad he doesn't have an Espeon (Sabrina's killed my Politoed,Marowak,and Lugia without dropping into yellow health.I had to use Draco Meteor, then parahax with Dragonbreath to defeat her-Dialga rules.)
Do you need HMs to get to him?Because if you do, I'll fail.Otherwise...
Marowak will Bone (merang) that Pikachu, Politaro (Politoed) will Surf over Charizard, Bounce Venusaur to death, then my Hypnosis+Substitute+Focus Punch Poli (Poliwrath) will pwn the other 3.Or, if not, Suicune might help