Glitch City is a glitch in Red, Blue, and Yellow. The player is seen in a mess of different game pieces (E.G. a tree, or block in a random location on the screen).
How to get there
1. Go to the Safari Zone in Fuchsia City.
2. Tell the guards that you want to go in the Safari Zone. Enter.
3. Go back outside of the Safari Zone and answer No.
4. Repeat last step (optional).
6. Turn off your system after fully saving, and then load to get back to the game.
7. Go back to the guards. They'll welcome you to the Safari Zone. Tell them No.
8. Walk out. The game thinks you are still in the Safari Zone.
9. Walk/ride your bicycle/surf in any route that doesn't have buildings in it (the glitch city is different depending on what route you are in) until you hear the PA's 'Ding-Dong' that will ring after you walk the amount of steps needed. You'll then be teleported to the Safari Zone, where the guards will tell you to come back next time.
10. Exit the room (door at the opposite side of the room) and you'll find yourself in Glitch City! If you did it on a route with a building in it, you will end up coming out of that building instead.