Here's why:
* Game saves are stored on the cartridge/game card: For a Nintendo DS game like Pokemon Diamond, the save data is stored on the game card itself, not on a website or online service.
* No central pin code system: Nintendo doesn't have a central system that uses pin codes to unlock or access games.
How to access Pokemon Diamond:
1. Insert the game cartridge: Put the Pokemon Diamond cartridge into your Nintendo DS console.
2. Power on the console: Turn on your DS and the game should start automatically.
3. Play the game: Enjoy playing Pokemon Diamond!
If you're having trouble accessing the game, make sure the game cartridge is clean and free of dust or debris. You can also try restarting your DS console.