By equipping a Choice item, Haxorus can unleash the beast within and maul its usual checks with its awesome power. By holding a Choice Scarf, Haxorus outspeeds and KOes faster Dragon-types, such as Garchomp and Latios, before they can act, which gives Haxorus more room to switch in and out so it can switch moves. Choice Band makes Haxorus a bit more reliant on team support, but boosts its already potent 218 Attack to a massive 327, which allows Haxorus to 2HKO threats such as 140 HP Zapdos, specially defensive Cresselia, Dusclops, and Togekiss with Dragon Claw or Dual Chop. Outrage is even more destructive with a Choice Band, OHKOing each of the aforementioned threats even if they have not sustained much prior damage. Unfortunately, Outrage isn't all that reliable because it selects its target randomly, but any opponent hit, bar Steel-types, probably won't enjoy taking huge amounts of damage. Earthquake is a staple spread move, but unlike other Earthquake users, Mold Breaker allows Haxorus to hit Levitating Pokemon. This is of course a double-edged sword, as this affects your own Levitators as well. Rock Slide is another staple move, but you might find its paltry 56 Base Power unappealing. Haxorus also has access to Brick Break and X-Scissor, which can be used to hit the occasional Ice- and Steel-types and Grass- and Psychic-types, respectively.
Dual Chop and Dragon Claw share the same 80 Base Power, though Dual Chop has a better chance to critical hit, and can hit through Substitutes, resist Berries, and Focus Sashes.However, Dual Chop has only 90% accuracy as opposed to Dragon Claw's 100%, and has higher chances of activating abilities such as Flame Body. The EV spread ensures that Haxorus outpaces neutral nature base 95 Speed Pokemon, such as Darmanitan, as well as Timid Smeargle. If you're concerned about opposing Haxorus, you can use a spread of 4 HP / 252 Atk / 252 Spe to outspeed those with the standard spread.
Choice Haxorus is more reliant on team support than other variants. Togekiss and Hitmontop spring to mind as good partners, either paralyzing and redirecting attacks or flinching the opponent and protecting Haxorus from Blizzard, respectively. Additionally, both Togekiss and Hitmontop have the option of boosting Haxorus's already devastating attacks to almost unimaginable heights with Helping Hand. Haxorus also appreciates having Zapdos or Thundurus as partners, as they are immune to its Earthquake, can support Haxorus with Tailwind or Thunder Wave and, in Zapdos's case, use Heat Wave to melt opposing Ice- and Steel-types. Feint, Taunt, Imprison, and Encore support is helpful to ensure that opponents don't Protect their vital Pokemon, ensuring a kill under Haxorus's claws. Because Haxorus might be switching in and out frequently to change its moves, it is important to have a Pokemon that can sponge, or is immune to, the attacks that Haxorus attracts. Shedinja, Ferrothorn, Suicune, and Rotom-W make great switch-ins, and the latter three can even slow down the opposition with Thunder Wave or Icy Wind.