How do you get Michael to wear shorts on Pokemon XD?

You can't get Michael to wear shorts in Pokémon XD: Gale of Darkness. Michael's outfit is fixed and doesn't change throughout the game.

The only way to change Michael's appearance is by using cheats, which are not recommended as they can disrupt the game's balance and potentially corrupt your save data.

Instead of trying to change Michael's clothing, you can focus on enjoying the game's story and gameplay as it is intended.