Catching mew old school style

[Sasuke]

I forgot how. Please refresh my memory and discuss.

[the master]

Hmm.. I have to find the site.

[the master]

Ok, didn't find the site but here's how to catch it on r/b/y:
First off, you need to have NOT beaten the youngster with the Slowpoke that is by Bill's house or the Gambler between Celadon and Lavender. Second, you must have fly. Be sure to have a weak Pokemon that can safely weaken a Pokemon at LV 7, or just take some Ultra Balls along. Go through the underground passage and as soon as you exit, don't move. Save at this point, because if you mess up the next step the whole glitch is ruined. Once you have saved, walk one step down and immediately press start. If you did it right the Gambler won't notice you. Go straight to the Pokemon status screen and fly to Cerulean City--you'll notice that once you start flying, the Gambler will get the little exclamation point over his head that means he noticed you. Once you have gotten there, you'll notice that your start button doesn't work--it's because the game thinks you are in a battle with the Gambler, and in battles, 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 that he will have to walk over to you when he notices you. Beat his Slowpoke, and your start button will work again. Fly to Lavender town. Go left--towards where the Gambler is--and when you get into route 8 your start menu will pop up all by itself. DON'T save, press B right away. When the start menu closes, you will be attacked by a LV 7 Mew! Catch it, and then rejoice.

[Pikatwo]

I forgot how. Please refresh my memory and discuss.

Google is always your friend.

[TheUnown5]

On Fire Red and Leafgreen:
Find the old sea chart or go to a nintendo event.(it's actually passed)