Guess What: I got my Pokémon Red Version for Game Boy, and with a little help from YouTube I caught Mew.
-All you need is
-A Game Boy
-Your Red Version
-A good pair of hands and a Brain
No Game Shark, not moving the SS Anne truck, no complete PokéDex, just do this:
-Get Fly
-DO NOT FIGHT THE YOUNG TRAINER on the way to Bill's house who is facing north, standing directly above a LASS
-DO NOT FIGHT the GAMBLER facing the entrance of the underground tunnel from Lavender to Celadon
-You MAY NOT fight the guy in the grass next to the bridge in Cerulean. Some sites say you must not fight him, but I did, and I caught Mew ().
Then:
-Save the game before you start.
-Fly to Lavender Town and walk West (to Celadon City). A few steps before the entrance, you'll see the Gambler (the one who looks like Voldemort)facing north to a house. Walk to the house, avoiding him of course, till he's offscreen.
-This is the most difficult part: Walk towards him, and, at the moment he appears on-screen, press START and fly to Cerulean City. If you do it right, the ! symbol will appear on his head after you're gone.
<-------------He's the GAMBLER
-Head for the YOUNG TRAINER. NOTE: HE MUST WALK TO YOU
-Defeat his Level-17-Slowpoke.
-Fly back to Lavender Town and walk west again.
-When you're in the narrow path leading west, your START menu will appear. Press B Button.
-Walk and inmediately Mew will appear.
He's level 7 and just knows Pound, so use that good-old ULTRA BALL to catch him. I caught him on Sunday, and by this day he's level 52.