This is a video showing how to use the walk through walls GLITCH in Pokemon Red/Blue. It is a subglitch of the main Glitch City glitch. THIS DOES NOT INVOLVE USING A CHEATING DEVICE.
Here are the steps you need to take to activate this glitch
1. Get a poisoned pokemon and deposit all other pokemon in the PC
2. Go to Safari Zone and pay $500 to play
3. Try to leave the Safari Zone, but when asked if you want to leave early, select no
4. Save the game and restart
5. Walk back into the Safari Zone building and walk downward
START COUNTING THE STEPS YOU TAKE
6. When asked if you want to play, select no and leave the building
7. Walk around and make sure you are on top of a ledge when you have walked 499 steps. Make sure you heal your pokemon with potions when it comes close to dying
HINT: Every time the screen flashes black, that is 4 steps, so count 125 screen flashes and 3 steps.
8. Jump off the ledge so you are in midair when you run out of steps
9. You will be back in the Safari Zone building and you can now walk through walls. Try it.
NOTE: DO NOT TRY TO LEAVE THROUGH THE EXIT. YOUR GAME WILL CRASH
10. Run around making sure you do not go off screen until your pokemon dies
11. You will be teleported to the last Pokemon Center you have been to
12. YOU CAN NOW WALK THROUGH WALLS