Games : Cheats for Pokemon Emerald (GBA)

I started playing Emerald few weeks back. I wanted to use cheats here. I had put the master code and the master ball code which works absolutely fine. But whenever I use pokemon code nothing happens. Keep in mind, I play On my Android phone in the GBA emulator(not the John lite version). Once I put the pokemon cheat and then use the PC in PokeCentre the game just freezes. I don't know what the problem is but when I searched about it many people claim that they had it worked in their cell phones.

Can anyone help me? Thanks on advance