I'm actually running this set but with 252 atk and speed. I use the Assault Vest to turn random ohkos into 2hkos like Gar's dazzling gleam, then counter kill them. It's also nice when a special sweeper's stab is only a 3hko on Chomp instead of a 2hko.I've been having a surprising amount of success with Assault Vest Garchomp. The opponent brings in some special sweeper expecting to get an easy super-effective KO (Ice Beam Clawitzer and Draco Meteor Goodra are the first things that come to mind...which is odd, since Chomp outspeeds them. There are definitely better examples, I just can't think of them off the top of my head. Also switches in on Fairies fairly (...ouch, pun not intended) comfortably). The set I'm running at the moment:
Garchomp @ Assault Vest
Ability: Rough Skin
EVs: 252 Atk / 200 HP / 52 SDef / 4 Spd
Adamant Nature
- Earthquake
- Dragon Claw
- Stone Edge
- Iron Head
Yes, I'm aware the EVs are dumb; they've never exactly been my strong suit. But Chomp has yet to be one-shot by a special attack (Specs Noivern D-Meteor or a STAB Ice Beam might do it, but that's about it), and it usually either gets the KO back (special attackers are squishy) or severely weakens the special attacker, which would probably make it a good Double Dragon pokemon, or just a general lure to draw out threats to similar attackers. Stone Edge hasn't seen much use, so I've been thinking of trying out either Fire Punch or Blast in that slot to hit Ferro/Skarm (Iron Head is usually enough to handle Togekiss).