Hey guys, do you have a problem when catching the mew? Yes, if you have GS/AR on your pocket. Huuh.
But, Problem solved!!! This guy at pokecommunity.com actually find this out.
So what you'll need is:
Hex editor (used HxD)
Fire Red rom, of course...
First open the rom. Then goto offset 1d402. You see the 97? It's a hex position for Mew. So you can change it with the pokemon from this page full of listings.I recommends 00 as this is DecaMarks Pokemon, a glitchy pokemon.
HOW THIS WORKS?
The Game checks if it a mew. IF setobedience is unset then game began trolling you.