Here's why:
* Compatibility: Pokemon Black was released for the Nintendo DS, not the 3DS. The 3DS is not backwards compatible with DS games.
* Cartridges: The game cartridges for the DS and 3DS are different sizes and have different connections.
However, you have two options to play Pokemon Black on a 3DS:
1. Nintendo 3DS Virtual Console: The Nintendo 3DS Virtual Console allows you to download and play classic DS games, including Pokemon Black and White. You can purchase these games from the Nintendo eShop.
2. Emulation: You can emulate Pokemon Black on a 3DS using a custom firmware. This involves modifying the 3DS system software, which can be risky and may void your warranty.
If you're looking to play Pokemon Black, the Virtual Console is the safest and most recommended option.