* DeSmuME: DeSmuME is a free and open-source emulator that can play Nintendo DS games.
* NO$GBA: NO$GBA is another free and open-source emulator that can play Nintendo DS games.
* MelonDS: MelonDS is a relatively new emulator that can play Nintendo DS games. It is still in development, but it is already very promising.
To get started with an emulator, you will need to download the emulator software and the ROM file for the game you want to play. You can find ROM files online, but it is important to note that downloading ROM files may be illegal in your country.
Once you have downloaded the emulator and the ROM file, you can follow these steps to play Pokemon Diamond on PC:
1. Open the emulator software.
2. Click on the "File" menu and select "Open ROM".
3. Locate the ROM file for Pokemon Diamond and click on "Open".
4. The emulator will start playing the game.
You can use the keyboard or a controller to play Pokemon Diamond on PC. The controls are similar to the controls for the Nintendo DS version of the game.
If you have any problems playing Pokemon Diamond on PC, you can consult the emulator documentation or search for help online.