I have just became a member of this society to inform you that I found out that there is a correction needed.
As you perhaps already know, catching Mew on pokemon Yellow can be quite a bind. This glitch can be also used to catch other random pokemons.
Today I found out that there is even a quicker way to glitch these random pokemon! In Mt. Moon there is a tunnel leading to a rocket which has the necessary elements to be able to perform the glitch! Since he is out of view at one point and when u take another step he shows up on your screen trying to challenge you. This is the rocket situated in the 2nd ladder down (counted from the entrance at the Pewter city side). After pressing start (I'm not going to explain the entire routine) you can use your escape rope that you found earlier on in the cave to exit the cave. Teleport away, let the glitch work it's magic and directly after teleing away re-enter the cave and find a trainer (plenty of 'em to choose from). Battle him and head back to the rocket. Upon entering the ladder that leads to the rocket, the final stage of the glitch will activate and a random pokemon (depending on which pokemon you battled last) will appear!
I hope this isn't old news since I don't want to make a complete(r) fool out of myself :p
I would like to make this change to the Bulbapedia website since they state the glitch is at the earliest executable in Cerulean city. I'd like to see my credentials then on that page (Yes I'm vain) but I have no clue how to do so... Can anyone help me?