Version-Exclusive Pokemon are Pokemon that is only found in the either version of the game. Those Pokemon couldn't be found and recruited in the dungeons until a Wonder Mail code involving the Pokemon is entered.
List of Pokemon Exclusive to PMD Red version
Those Pokemon are absent from the Blue Version until a Wonder Mail code involving them is entered.
List of Pokemon Exclusive to the PMD Blue Version
- Porygon2 (could be obtained in the Red Version by evolving Porygon)