These fighting Pokémon first appeared in Pokémon Red and Blue. And all that time, they kept something hidden.
Yesterday, on an official Pokémon website, Machamp finally came clean:
The secret? As it says above, neither Machamp or Machoke are wearing pants. Those pants are part of their markings, but not actual briefs. Yep, that's right, they are pantless.
This is because your typical Pokémon does not wear clothes.
Top image: The Pokémon Company