Pokémon Ash Gray is a fan-made ROM hack. It does not contain the original Nintendo copyrighted game data. However, to play it, you must provide your own legal copy of the Pokémon FireRed (U) (V1.0) ROM.
Secure your clean FireRed ROM, apply the 4.2 patch, and set out from Pallet Town – as Ash, for real this time. Pokemon Ash Gray Version 4.2 Download