Never mind. Just found this thread (https://www.pokecommunity.com/showthread.php?t=18612) which shows all the teleport locations. When I get home from work I'm going to try them all out and I'll possibly make a video on it.
I remember when I was in my early teens (around 2007-2009) I watched a youtube video where a guy was in a beta area or a inaccessable area via walk through walls in Leaf Green where there was weather effects and test NPCs. I was wondering how I can find the area because I love exploring glitch areas and this has been one in the back of my mind for bloody ages