Hax "R" Us
If you see a Pokémon with axe-shaped tusks, be prepared because s*** is about to get real soon... and that's gonna hurt a lot!
About Haxorus, it's my fourth favourite Unova Pokémon (the first three places were taken by Hydreigon).
Ability Compendium:
Rivalry: Attack & Special Attack is increased by 25% if the foe is of the same gender; Attack & Special Attack is decreased by 25% if the foe is of the opposite gender.
Unreliable Ability, you don't know the gender of the opposing Pokémon unless you actually battle with them and you know as well as I that we can't risk an attack drop if you face a Pokémon of opposite gender.
Mold Breaker: (RECOMMENDED) The Pokémon's moves are not affected by foe’s abilities during battle
Must have Ability, it negates some Abilities like Wonder Guard or Levitate
Unnerve: The opponent Pokémon will never use their held Berry while the Pokémon is in battle
Pros:
DAT Attack stat (147) makes Haxorus the third non-Legendary Pokémon with the highest Attack stat (the other two are Rampardos and Slaking)
Decent Speed (97) which can be boosted by Dragon Dance
Unlike most Dragon-types, which have a 4x Ice weakness, everybody's favourite axe-shaped tusk Pokémon has a 2x Ice weakness
A nice offensive movepool
Cons:
Decent Speed makes him slower than some of the top threats, however than Con becomes a Plus after one (or two if you get lucky) Dragon Dance
Slightly lower than average Special Defense (70)
Loses the best Dragon-type design to Hydreigon (but that's not important)
@Life Orb/Lum Berry/Persim Berry
Ability: Mold Breaker
Nature: Jolly
EVs: 252 Atk/252 Spd
Dragon Dance
Outrage/Dragon Claw
Earthquake
Aqua Tail/Brick Break/Rock Slide
Straightforward set, you can't go wrong with that. Switch-in against something that can't do much against Haxorus, use one Dragon Dance (or two if you get lucky) and then sweep.
Outrage with 147 Attack and 1-2 Dragon Dace(s) will obliterate at the very least 2 Pokémon even if one of them is a Steel-type, after 2-3 Outrages, Haxorus will be confused (Lum or Persim Berry in that case), if you don't like Outrage (like me), Dragon Claw is a significantly weaker alternative (Life Orb can compensate some of the power loss for not choosing Outrage).
Earthquake is Earthquake, I don't even need to explain what that move does and with Mold Breaker say goodbye to those pesky Levitators (and Shedinja).
The coverage move covers (duh!) certain threats... there's no Superpower for one single reason, the self-Attack drop goes again this set, also Aqua Tail bypasses Storm Drain and Water Absorb.
The Nature and EVs maximize Haxorus's Speed.