Machamp is a pure Fighting-type Pokemon, meaning he is only weak to Psychic, Flying and Fairy. Use these types of attacks to gain an advantage during battle. On the other hand, Machamp is resistant against Rock, Bug and Dark-type attacks, so be sure to avoid using these types of attacks.
As a pure Fighting-type Pokemon, Machamps attacks are also mostly Fighting-type. Choosing a Pokemon strong against Fighting-type attacks is very much recommended as Machamp has a very high attack stat.
Alakazam is a Psychic-type Pokemon, meaning he is resistant to Machamp's Fighting-type attacks, and his attacks are super effective against Machamp. Combined with his incredible attack stat, he is the perfect Pokemon to quickly take down Machamp.