How to catch Mew in Pokemon Red/Blue and Yellow using the 'Mew glitch'

The Mew Glitch!

First I should point out that this glitch is completely safe and will not damage or corrupt your game save. This glitch is 100% legit and will work if you do it right and follow this guide,but it was not intended by the developers. Oh, and also, this glitch doesn't work on the remakes of the original game, Fire Red and Leaf Green, it only works on the original Red, Blue or Yellow.

About Mew:

Mew is the 151# pokemon and cannot be caught anywhere on Pokemon Red, Blue or Yellow. Mew was made as a bonus pokemon to the original series and could only be obtained by going to Pokemon events organised by Nintendo. Mew is a psychic pokemon that can learn all TMs and HMs. Yep, every single one of them. I have been using Mew for a while now on Pokemon Blue, and I can honestly say I have never had a better pokemon on any other Pokemon game than it.

Preparation:

Unfortunately, to perform this glitch it is likely you will have to restart your game, unless you haven't battled the two trainers you are not supposed to battle (see above to find out who these are) or you haven't got very far in the game yet.

What you will need to perform the glitch:

• A pokemon that knows fly (You can obtain HM02 Fly by going east from Celadon city, towards the cycling road and using Cut on the little tree just before the Snorlax. Fly is given to you by the woman in the little house.)
• To not battle the trainers on Route 25, just after Nugget bridge, and the gambler standing north towards the underground passage on route 8. See the pictures above to see exactly who I am talking about.
• A few ultra/great balls to catch the Mew. Mew is level 7 so bring a level 5/6 pokemon along to reduce his health a bit if you want to.

And finally, how to do the Mew glitch:

• Stand at the door of the underground passage on route 8 and make sure you save the game. Take one step southwards and immediately press start. If you pressed start quick enough, the gambler shouldn't start a battle with you. If he sees you and battles you before you press start, turn off your game and then back on, and repeat it again until the menu appears without him seeing you.
• Now your on the menu, fly to Cerulean city. As you fly away, the gambler should just see you, but don't worry, this is normal. Walk to the top of nugget bridge and battle the trainer in the picture above (I believe he is a Youngster?). Note that you can't walk straight in front of him and battle him, you have to walk at least two steps away from him, so he walks to you. If you don't do this your game will freeze, but don't worry, it won't corrupt your game save. The trainer should have a Slowpoke, level 17.
• After you have beat the trainer, fly to Lavender town and walk towards the narrow path to the west of you. Note that your start button won't work from here. Take one step into the narrow path (see picture below), and your menu will pop up without you prompting it. Exit the menu and Mew should randomly appear! Mew is a level 7 and only knows pound, so he should be easy to catch.
• After you have caught him your start button should work as normal and so should everything else. You can level up Mew, use him in battles, practically do whatever you want with him. Thanks for reading and I hope this helped!