NLZ-GBA Advance is a GBA graphics viewer and editor.
Compatible with: Pokemon Ruby, Sapphire, Emerald, FireRed, LeafGreen
Supported OS: Windows
If you think your overworld is too small or too big and want to resize it to your conditions, use Overworld Changer.
Even one small detail like the foot print of Pokemon can also be edited with Foot Print Editor (FPE for short).
With a simple-designed interface for even a beginner can use, this tool can change the number – the name – the description – the special values of that item.