Alright so you go to the gambler by the UndeRground pass and go down and press start and fly 2 lavender and go battle a person in the tower and go to the path on the left side of the city and the menu will pop up press b and get ready DONT I REPEAT DONT CATCH OR KILL HIM IT WILL GLITCH YOUR GAME[oh and go to youtube and type in pokemon yellow mew and watch the video it is real]