I saw a thread a while back about an emulator to play different gameboy games but no one could find one that works. My friend found one that works perfectly and it's so fun.
1. Go to settings and then date and time. Switch the set automatically switch to off and change the date to 2012.
2. Go to coolrom.com on iphone and hit the little phone icon in the top right.
3. Then choose your device and download the gameboy advance option.
4. Once downloaded, open and hit the icon in the top right. Then you can choose which games to download (pokemon) and have fun!
Also after everything is downloaded switch the back, or you won't be able to send messages/make calls.