Instructions
Open Visual Boy Advance.
Click the "File" menu and then click "Open" to load the game you want to play. The GameShark feature does not work if you do not load a game.
Click "Cheats," "Cheat List" and then "Gameshark."
Refer to the "Resource" section to find a cheat code website that features GameShark cheats. Find the Gameboy game you're looking for, and then scroll down the page to a section called "GameShark Codes." Copy those cheat codes by highlighting the codes with your mouse and then clicking "Copy."
Go back to VBA. Paste the GameShark code into the field that is blank and then click "OK." The code you enter will have an "E" by it, meaning that it is enabled.
Click "OK" to work GameShark for VBA.