Blastoise d for weakness. Nidoqueen d for an extra attacker (vengence is good for lat game with boost), accelerates setup as well. Altaria Ex for covering weaknes and accelerates setup. Castaway with buffer piece and metal energies is helps you stay alive. Mawile PK is a nice starter to get basics and a devastating second attack? Metagross' power is a major hand disruption and can combo with steven's, wager, copycat, oak, rowan and anything else that would let you add to your hand, reshufle or hinder your oponents hand further. Warp point and switch help out so much. Warp is better because you can fors them to bring out the pokemon you want to hit. All you need after that is a good list and you have a succefully made a T3 Metagross Ex deck.