eBay is full of fake Pokemon Gameboy Advance games. I just bought Pokemon FireRed and luckily, it was the real deal. Sometimes people get fooled by stock photos. It's kind of hard not to come across one. And here are a couple of ways to avoid buying a fake cartridge.
1. Avoid buying the bundles of every Pokemon GBA game in it, they attract a lot of people!
2. Look at the sellers location, if it says CHINA. Don't buy it
3. Look for a rectangle on the back if the cart. I will post a pic.
These are easy steps on how to get the game you want. Leave more in the comments to help People!