Made of Metal, surely, but Gross... It isn't
Ability: Clear Body
Item: Choice Scarf
EV's: 252 Atk, 252 Spd, 4HP
Nature: Jolly or Adamant
Metagross has decent Speed, but it may need more, hence the Jolly option and Choice Scarf. Zen Headbutt and Meteor Mash are for STAB. Earthquake gives Fire-Types a hard time, and Ice Punch covers your remaining weakness, Ground.
-Meteor Mash/Gyro Ball
Brave, Sassy or Relaxed (I personally prefer Brave, but...)
252 Atk, 151 Def, 151 SDef, 4 HP
This set does well with a team with members like Slowking, Shuckle, Bastiodon... With 0 Speed EV's, Iron Ball and a Speed-Hindering Nature, Metagross outslows lots of Pokémon. With 0 Speed IV's that would give you 130, but with Iron Ball... 65. Obviously, set up Trick Room. Gyro Ball is better with Low Speed, but Meteor Mash has more PP and can raise your Attack. Zen Headbutt is for STAB too. Earthquake so you get rid of Fire-Types, or Ice Punch for Ground-Types.
I suggest Spiritomb for POTW #108.
Unfortunately, metagross doesn't learn trick room, so another pokemon has to set it up