^This
I like this set because so many people have no idea what to do with Mawile. My only suggestion is slashing Iron Head with Swagger so you aren't Taunt bait, otherwise someone could Taunt you, switch, and start setting up on Mawile. This way, you have a way of keeping some offensive presence.
I would also use Hyper Cutter over Intimidate, or Encourage if you go with Iron Head. The reason is that Intimidate gives away the fact that Mawile is using a defensive set.
It's too bad Mawile's stats are awful, it has the right movepool to succeed and its cute, too. Gamefreak, y u no give Mawile good stats?
I'm going to say I ran a Mawile similar to his set and it ended up turning out pretty good, scoring at least 1 if not 2 kills per game.