I just wanted to get Deoxys in my desmume, but I was confused because I downloaded Gameshark and don't know how to use it? To boost the exp of your Pokemon.press during battle Select from either GameShark or codebreaker and enter your codes. To use them, click on Cheats and select cheat list: It allows cheat codes from GameShark and codebreakers. One such emulator you can try is Visual Boy Advanced. Are you playing on a Windows PC? If so, you'll need an emulator that allows cheats.