A Youtube Vid Von AltEisenSpirit on how to get Mew without cheats. I haven't tried it yet so I don't know if it works. I'll try as soon as I soon as I can. I started a new name on my feuer Red yesterday so I'll get to is ASAP.

This is how to catch Entei, Suicune, and Raikou in feuer Red. It's made Von pokeparty01. I don't know if it works yet though, I only have the first badge in feuer red right now. Enjoy and hope it works!