Well i was dawdling about the net as usual on a lazy saturday afternoon, when i found this, and it was so well written and convincing, that i believed it, i haven't tried it yet but have a feeling it may work!-

I have found a way to catch Mew. It really works, I have done it myself. You may have to start a new game to do it but it's really worth it! Anyway, here's how it goes. You know that Youngster (at route 25), the one by Bill's house that has a Slowpoke at level 17? You cannot battle him or this glitch will not work! You also can't battle the Gambler between Lavender Town and Saffron City (at route 8). The Gambler has two Poliwags and a Poliwhirl, just so you know who he is. And one of your Pokemon in your party must know Fly. Have lots of Ultra Balls. Okay, go through the Underground passage that leads to Route 8. Once you get out the door and you're at Route 8, just stand there and don't move. Save your game right here. Once you have saved, walk down and immediately press start. If you did it right, the Gambler won't notice you. After this, Fly to Cerulean City. You'll notice that when you start Flying, the Gambler will get the little exclamation point over his head which means that he noticed you and wants to battle. OK, once you get to Cerulean City, you will notice that your start button doesn't work. This is because the game thinks you are in a battle with the Gambler, and in battle the start button doesn't work. Walk up Nugget Bridge and find the Youngster, but don't walk right up to him, or the game will crash. Walk up so he will have to take a few steps when he notices you. Beat his Level 17 Slowpoke, and your start button will work again. Fly to Lavender Town. Go left, to route 8, and your start menu will pop up all by itself. DONT SAVE. Press B to exit the start menu... and you will be attacked by Mew! It's at level 7, and its only attack is Pound. After you catch Mew, rejoice!

You're over two and a half years late with that.

Woot, you see the fact is, i found my GBC 2 days ago, in the closet, and i hadn't saw it in atleast 4 years, so basically im 4 years behind schedule