How do you get shaymin in Pokemon diamond before the elite four?

You can't get Shaymin in Pokemon Diamond before the Elite Four. Shaymin is only available in Pokemon Diamond and Pearl through an event that required a special Wi-Fi connection to the Nintendo Wi-Fi Connection service, which was discontinued in 2014.

Here's why you can't get Shaymin in Diamond before the Elite Four:

* Event-exclusive: Shaymin was distributed through a special event that required a Wi-Fi connection and a specific code. You cannot get it in the regular game.

* Event ended: The Wi-Fi Connection service was discontinued, meaning the Shaymin event is no longer accessible.

To get Shaymin now, you would need to:

* Trade: Trade with someone who has a Shaymin from an old event.

* Emulation: Use a ROM with a hacked version of the game that has Shaymin already available.

Remember, using hacked games can be against the spirit of the game, and it's important to be aware of the risks involved in using emulators.