Ok, this is really cool. First of all, to get mew, don't fight the youngster trainer northeast of the nugget bridge.(he's the one where you can choose to fight him or a girl so fight the girl). Also, dont fight the guy south of the underground path from Lavender to Celadon. Ok, now we're ready. Get to the entrance of the underground path that i said earlier but dont go down!!! I would save in case you mess up. Go down and immediately press start. Fly to Cerulean and the guy will see you fly away. Fight the youngster trainer i said earlier but make sure he has to walk up to you. Dont go and talk to him or the game will freeze. When you beat his lvl 17 Slowpoke, fly to lavender. Go west until you get the to path that connects the route from the city. The menu will pop up by itself. Press B to exit and a battle will start. It will be a lvl 7 Mew that only knows pound. It is really hard to catch(since you cant really attack it without killing it) so try your best. This worked for me and mew can learn almost any TM. I have a lvl 13 that knows rock slide, tri attack, and pound. Its stats are incredible because my lvl 13 beat a lvl 30 Snorlax and i only used mew, no other guys. Its health is also amazing, at lvl 13, its health is 52. HOPE THIS HELPS!