Here's why:
* Arceus is the "Alpha Pokémon": Arceus is considered the creator of the Pokémon universe and is incredibly powerful. It has the ability to control all types of Pokémon and can change its type at will.
* Arceus's stats: Arceus has exceptionally high stats, especially in its base stat total. It is considered one of the strongest Pokémon in existence.
* Machamp's limitations: While Machamp is a powerful Fighting-type Pokémon, it is ultimately limited by its type matchups and its overall stats compared to Arceus.
In short, the difference in power between Arceus and Machamp is simply too vast. Arceus would be able to defeat Machamp with relative ease.