You can do it in Japanese Red, Green, and Japanese Blue. I just posted 13 pictures of 2 Green Glitch cities in the Glitch sticky.
Step 1. Goto the Safari Zone. Then walk back inside the entrance, the guy will ask you if you want to leave, say no.
Step 2. Go back in again and say no again. Save and restart.
Step 3. This time he will ask you if you want to pay to get into the Safari Zone. Say no. Fly to Cinnabar and Surf up and down the half-land-half-sea area until the 500 steps are up.
Step 4. The PA will call you and you will be transported back in to the Safari Entrance, walk out and you'll be in one of the Glitch Cities.
Do not save in Glitch City unless you have a Pokemon with Fly otherwise you're trapped forever =D
Glitch Cities are in different areas too try these: Route 1, Pallet Town, Cycling Road
Those are the others I did I'm sure theres more but not every place winds up in a Glitch City.
