This glitch was discovered by RingRush and Werster in 2011 and occurs when you obtain 22-29 Pokémon in the party with ????? (00) party overloading (possible for example with a bad clone). The more Pokémon you withdraw the more you can corrupt.
By viewing your overloaded party and exiting it, it is possible to partially transform the map into a Glitch City, allowing you to do a number of sequence breaks by walking on new passable tiles.
Notably we can take the train to Saffron City without a Pass and go all the way to the Pokémon League to beat the first half of the game with only 2 Badges.
While on the party, it is sometimes possible to exit out with B but for unknown reasons this doesn't always work. If it doesn't view the summary of the first Pokémon and scroll down to the bottom. After reaching the bottom exit the summary and press down once and then A to exit.
If you don't get a favourable corruption you can go to the bottom Pokémon in the menu and switch the Pokémon about three spaces up or so to adjust how the map is corrupted.
Additionally if you put part of the Glitch City off the screen saving and resetting may restore that part of the map back to normal, which is useful to get the right corruption in certain cases.
1. Party Pokémon 17 (dbff) - Sixth OT character greater than 3 (use any five+ long OT name or a trade/gift Pokémon (see below))
2. Party Pokémon 21 (dc2f) - Tenth OT character greater than 3 (we can use an in-game trade Pokémon like Goldenrod Department Store's Machop or Randy's Spearow north of Goldenrod City to meet this requirement or a Pokémon caught from a Generation I game where a preset name was used. The preset name must actually have been selected from the menu)
3. Party Pokémon 20 (dc5f) - Pokémon nickname third character greater than 3
4. Party Pokémon 24 (dc8f) - Pokémon nickname seventh character greater than 3
If you don't meet these requirements the game may simply lock up upon trying to view the party (possibly with a white screen if not in a Glitch Dimension).
2 Badges run skips
The skips required for a 2 Badges beat Lance run are as such:
1. Train station skip (enter left-most door to get to Saffron City).
2. Snorlax skip (from a little west of Snorlax you can walk into Diglett's Cave without removing the Snorlax)
3. Route 2. North of Viridian City outside of Diglett's Cave (only if you don't have a Pokémon with Cut and the badge required to use it)
4. Route 22 gate to enter Victory Road.
5. A map distortion is needed at the end of Victory Road to avoid the battle with Silver.
If you want to beat the Elite Four you'll need to faint your top six Pokémon, swap ????? 00 to the bottom of the party and then continuously deposit Pokémon 2 until you get a message saying you've run out of usable Pokémon.
From then on every battle will result in an instant victory.
In order to faint the top six Pokémon you'll have to view the summary of the first Pokémon and scroll down first, leaving the top Pokémon to faint last. After the top Pokémon faints run away. If you fail to run away you'll have to restart the game and try again because the party cursor gets locked on Pokémon 1.
Upon entering the Hall of Fame the game may simply skip showing the Pokémon. This may also apply to Hall of Fame from the PC menu.