I'd put Agility on it, personally. Many Pokemon would set up Swords Dance or attempt to 2HKO with Earthquake. Use Agility to set up, have Metagross holding a Sitrus Berry or Leftovers for survivability, and with that Speed boost, 60 Speed EVs, and a Neutral nature for Speed, Metagross will outrun most of the unboosted metagame from one turn of setup.
My second choice would be Trick + IB. Trick sets can backfire easily though. If you trick a Choice item onto yourself, then that could be a hassle in sweeping. You could trick yourself an essentially useless item, or even trick a Trick Set Pokemon, and end up with an Iron Ball again. Trick is a move that has to be used very carefully. It's useful, but you almost never get to carry a sweep because of it.