In "Pokémon" you are a trainer collecting cute but deadly creatures to battle against gym leaders, lesser trainers, and friends. Generation III of "Pokémon" (Ruby, Sapphire, and Emerald) introduced Pokémon abilities. Some of these abilities are always active, others require special circumstances, but all of them are in addition to your Pokémon's set of four moves. Unlike moves, there are no items or level achievements that will teach your Pokémon new abilities. Even though some Pokémon have two different moves possible, you cannot change an ability that is already learnt. Machamp is one such Pokémon. To change Machamp's ability from "Guts" to "No Guard" you must capture a new Machoke or Machop that has the No Guard ability and evolve it into a Machamp.
Capture a Machop. This step only applies if you are playing "Pokémon Ruby", "Sapphire", "Emerald", or "White". If you are not, skip to step two. Machop is commonly found on both Fiery Path and Jagged path in "Ruby", "Sapphire" and "Emerald". For "Pokémon White," he can only be found in the White Forest. After capturing your Machop, ensure that he has the ability No Guard and not the ability Guts. Because there is no way to change abilities, if he doesn't have No Guard then you must release him and repeat this step. Battle your Machop until it evolves to Machoke. Skip to step three.
Travel to a location where Machoke are commonly found. For Pokémon "FireRed" or "LeafGreen," this is Cerulean Cave, Mt. Ember, or Victory Road. For "Pokémon Diamond", "Pearl" or "Platinum," try Routes 210, 211, 225 or 216. For "Pokémon HeartGold" or "SoulSilver," try Cliff Cave. Battle until you capture a Machoke. If your new Machoke has Guts instead of No Guard, you must repeat this step.
Find a friend to trade with. Machoke can only be evolved into Machamp through trade. After the trade, have your friend trade him back to you; you are now the proud owner of a Machamp with No Guard.
Because No Guard makes every attack always hit and Dynamic Punch always causes confusion; many trainers pair No Gaurd with Dynamic Punch on Machamp.
Neither Machop or Machoke can be captured in Pokémon Colesseum, XD, or Black. For those editions of Pokémon, you must trade for it.