Here's why:
* Different Games: Paper Mario is a series of role-playing games developed by Nintendo, while Pokemon Pearl is a monster-catching role-playing game also developed by Nintendo. They are distinct games with different gameplay and storylines.
* No Character Customization: Pokemon Pearl doesn't allow players to create or customize their own character to be Paper Mario. You play as a trainer with a set appearance.
You can't directly play as Paper Mario in Pokemon Pearl, but you can still enjoy both games for their unique experiences.