If you want a permanent change to how the game handles experience, "fixed" patches are the preferred method for many in the ROM hacking community.
(held item) by catching wild Chansey in the Safari Zone, which provides a legitimate 1.5x EXP boost. or instructions for a different multiplier How to Level Up FAST in Pokémon FireRed & LeafGreen pokemon fire red exp multiplier x2 fixed
Pokémon FireRed : Troubleshooting and Fixing the 2x EXP Multiplier If you want a permanent change to how
These codes are intended for the of Pokémon FireRed (Code BPRE ). Using them on other regions (like European or Japanese versions) may result in the game crashing or the code not working. pokemon fire red exp multiplier x2 fixed