ShootingStarmie
Bulletproof
To be honest, I like to think that a lot of Pokemon in the BW2 metagame are un-counter able. Like the above poster said, Haxorus can get past Skarmory, considered to be it's best counter. That being said, in BW2 OU, we often find ourselves checking threats with priority, faster Pokemon, or bulky hard hitters. So, the best way to deal with Haxorus is with a Choice Scarf user, or priority. Here are some examples
Mamoswine @ Life Orb
Trait: Thick Fat
EVs: 252 Atk / 4 SDef / 252 Spd
Adamant Nature
- Ice Shard
- Icicle Spear
- Earthquake
- Superpower
Mamoswine easily beats Haxorus one on one with it's powerful Ice Shard. While Mamoswine can't switch in directly, it easily forces it out. Mamoswine can even revenge kill boosted Haxorus, thanks to priority ignoring speed tiers.
Scizor @ Choice Band
Trait: Technician
EVs: 252 Atk / 252 HP / 4 SDef
Adamant Nature
- U-turn
- Bullet Punch
- Pursuit
- Superpower
Scizor is probably one of Haxorus' best checks, as it can come in on Haxorus' attacks pretty nicely, and can revenge kill Haxorus even if it has set up. It also makes the Haxorus user think twice before spamming Outrage.
Garchomp (M) @ Choice Scarf
Trait: Rough Skin
EVs: 252 Spd / 252 Atk / 4 HP
Jolly Nature
- Outrage
- Earthquake
- Stone Edge
- Dragon Claw
Garchomp naturally out speeds Haxorus, and easily forces it out as even at +1 thanks to Choice Scarf making it faster still. Garchomp is bulky enough to switch into Haxorus' attacks bar Outrage, so it's a pretty decent check.
So yeah, checking Haxorus is a much easier job than outright countering it.
Mamoswine @ Life Orb
Trait: Thick Fat
EVs: 252 Atk / 4 SDef / 252 Spd
Adamant Nature
- Ice Shard
- Icicle Spear
- Earthquake
- Superpower
Mamoswine easily beats Haxorus one on one with it's powerful Ice Shard. While Mamoswine can't switch in directly, it easily forces it out. Mamoswine can even revenge kill boosted Haxorus, thanks to priority ignoring speed tiers.
Scizor @ Choice Band
Trait: Technician
EVs: 252 Atk / 252 HP / 4 SDef
Adamant Nature
- U-turn
- Bullet Punch
- Pursuit
- Superpower
Scizor is probably one of Haxorus' best checks, as it can come in on Haxorus' attacks pretty nicely, and can revenge kill Haxorus even if it has set up. It also makes the Haxorus user think twice before spamming Outrage.
Garchomp (M) @ Choice Scarf
Trait: Rough Skin
EVs: 252 Spd / 252 Atk / 4 HP
Jolly Nature
- Outrage
- Earthquake
- Stone Edge
- Dragon Claw
Garchomp naturally out speeds Haxorus, and easily forces it out as even at +1 thanks to Choice Scarf making it faster still. Garchomp is bulky enough to switch into Haxorus' attacks bar Outrage, so it's a pretty decent check.
So yeah, checking Haxorus is a much easier job than outright countering it.