There are a few ways to use the rare candy cheat on a GBA emulator. The first way is to download a pre-made cheat file that can be loaded into the emulator. This method is the easiest and quickest way to get started using cheats with an emulator.
The second way is to manually enter the cheats into the emulator yourself. This method requires a bit more work, but it's still relatively easy to do. Simply open up the cheat menu in the emulator and type in the codes for rare candy.
Once you have either downloaded a cheat file or entered the codes yourself, you'll just need to load up your game and start playing! The rare candy cheat should now be active and you'll be able to use them as you please. Just remember not to abuse them, as they can make games too easy and take away from the fun.