The term "PS2" refers to the Sony PlayStation 2 console, not a Digimon. Digimon World 4 was released for the PlayStation 2, but the game itself doesn't have any Digimon named after game consoles.
Do you perhaps mean a specific Digimon that you're having trouble evolving? If you can tell me the Digimon's name and any specific requirements you're having trouble with, I might be able to help you find the right evolution path.