You Can't :(
But you can get Mewtwo in Cerulean Cave!!
they say you cant but i encountered him in cerulean cave on my way to capture mewtwo. the only way to catch him is to use a master ball. you only get one in the game so you need to give it to a Pokemon to hold, trade your Pokemon to Pokemon emerald the go to battle frontier. once there you have to save your game and put the Pokemon with the master ball in your box. either you turn it off while your in the box or you save your game and shut off in the middle of saving. if the cloning works then you will have 2 of the Pokemon and 2 master balls. make sure you know how to do it because if you do it wrong you could lose your Pokemon and ball. oh and emerald is the only game with the cloning glitch.
You can't get mew in firered or leafgreen.
There no Mew in firered.
You must capture Mew on Emerald and trade it to FireRed.
how did u get mew
You cannot get Mew legit in Pokemon FireRed, for the event for Mew has ended. You would need to use a GameShark or trade for it from Pokemon Emerald.
mew
no
Its not possible to get mew in firered only emerald can via Nintendo event.
Mew cannot be found in firered only emerald can via Nintendo event.
definitely Mew. but if you can't get Mew then probably Charizzard
Mewtwo, yes, if you have a FireRed or LeafGreen with Mewtwo.
if you want a cheat on how to get a mew on your first trip to cerelean city go to youtube and search how to get a mew in leafgreen or firered. or simply type mew(never tried that) ^^