Cheat for Pokemon Emerald causes the game to freeze on the Android GBA Emulator?
What probably happened to you is a "Bad Egg" has appeared in your pc, causing your game to freeze. Basically, bad eggs have a chance to appear when you cheat and getting rid of them isn't that easy. If you want to research more about bad eggs, you can read about them more in this link. Bad Egg
Here you can see more about how to get rid of them. Getting Rid of Bad Eggs in Pokémon Emerald