There's a version of Xerneas that knows rainbow force. Base damage is only 10, but 30 damage for each different type on the bench. Throw in sky field to increase your bench from 5 to 8 and go to town. Having split types like the water/fairy Azumaril and the fire/water Volcanion EX only boosts it further because those individual cards count as both types! Although competitive decks will call for stuff like hoopa ex and shaymin ex and other high cost cards, you can easily make a low budget casual deck that will be very effective.