Ya don't need cheats (alternative to various cheats)
That's right. Ya don't need cheats. They can also corrupt your file, break your emulator, and often they don't work. Here is an alternative for Wild Pokémons, Events Islands, warps, even map editing, and moore.
AdvanceMap. Spoiler:
Advance Map lets you edit maps, walk through walls, change sprites, recall places, warp to zone that you can't even access (example: Battle Frontier), create new places, decide which Wild Pokémons will appear, change music, and more.
AdvanceMap, copyright to LU-HO. If LU-HO is reading this, well, you're a genius.
More tricks, tips and cheats for this game are right here - Pokemon Emerald cheats