- Attack is increased 50% when hit with a status move.
Level 100 Statistics (see level 5, 50, 100)
Machamp's ability to OHKO Salamence and Skarmory—if it gets lucky with critical hits and Cross Chop's miss rate—is quite a plus. However, Cross Chop's low PP and subpar accuracy hinder Machamp significantly. While it is an easy switch-in to many Pokemon, Machamp is so slow that it can't really sweep.
Machamp makes for a strong but slow Choice Band user. With maximum Attack investment, STAB Cross Chop, and enough luck to score a critical hit, Machamp can OHKO Salamence and Skarmory. A Guts-boosted Focus Punch—perhaps activated by Thunder Wave from Blissey or Will-O-Wisp from Weezing—OHKOes Skarmory as well. Facade can seriously damage Weezing if you have trouble with it, while Hidden Power Ghost eliminates Gengar and Psychic-types.
Choice Band variants can run more Speed to beat Skarmory; Machamp will need about 128 EVs. Always use an Adamant nature.
Machamp has the defenses to set up Bulk Up boosts on Snorlax and Tyranitar. A boosted Cross Chop hurts as usual, while Hidden Power Ghost dents the likes of Gengar and Celebi. Rest is a possibility in the last slot, but Machamp doesn't have the Special Defense to pull off such a Curselax-like set. Putting EVs into Special Defense isn't such a bad idea, however.
Sleep activates Guts, which gives Machamp a huge Attack stat. These moves and EVs give Machamp some durability, and it can even function as a Tyranitar counter of sorts, and also as a good switch-in to Snorlax. Guts-boosted Cross Chop hurts just about everything, while Rock Slide takes care of Flying- and Ghost-type switch-ins; Dusclops and Weezing can't do much to this Machamp. Sleep Talk also gives Machamp on average five to six more uses of Cross Chop, which is useful with its low PP.
It can Encore boosting moves such as Calm Mind and Dragon Dance, which is very helpful alongside Substitute. Also of note is Light Screen, which can help Machamp gain a few Bulk Up boosts. Counter nabs a quick OHKO on Skarmory and non-Choice Band Salamence. Hidden Power Bug is handy for getting rid of Celebi on the switch, but Machamp will need a Choice Band or some other kind of Attack boost to OHKO.
Checks and Counters
Machamp has no surefire counters. Your best bet is prediction, and to hit it hard before it hits you, which is doable since Machamp is rather slow and has only average defenses. Gengar can come in on any Fighting move nicely, but will be 2HKOed by Rock Slide and usually OHKOed by Hidden Power Ghost. Dusclops is sturdier, but unlike Gengar, he cannot really hit back that well. Note that both these Ghosts should not Will-O-Wisp Machamp, as this will only make it more powerful. The same goes for Weezing; it must beware of inflicting status on Machamp with Sludge Bomb or Will-O-Wisp. If Machamp packs Facade, Weezing is dead, but it can otherwise take hits well and Pain Split off damage. Celebi makes a good counter overall, as Machamp cannot 2HKO it without Hidden Power Bug or a boosted Hidden Power Ghost; Celebi can use Recover or Leech Seed to heal, or attack with STAB Psychic. Salamence and Gyarados have Intimidate to lower Machamp Attack, and resist Fighting moves as well. Rock Slide can 3HKO them even after Intimidate, though. Finally, Skarmory is generally a reliable switch-in to Machamp, but note that a Choice Band-boosted critical hit Cross Chop will OHKO both it and Salamence.
Basically, your safest bet is switching around with common sense, and not giving Machamp too many opportunities to come in. Sand Stream ruins Machamp's durability even more.