Glitch City Laboratories Archives

Hey Chickasaurus! I have recently come across an oversight in Pokémon Gold that I wanted to share with you.

When the player saves the game through the start menu, changing boxes, Move Pokémon w/o Mail, or link communications, a new save will be initialized if a previous save does not exist, or if one does exist and the trainer ID is different. Initializing a save includes erasing Pokémon box data and placing a terminator ($FF) at the start of each box's list of Pokémon.

There is another way to save the game: by entering the Hall of Fame. The save operations performed there do not check to do initialization if needed, leaving Pokémon box data as is, but still otherwise saves the game which meets the criteria for "initialized". The player will then have access to the existing Pokémon box data since the other operations will no longer erase it.

Here are three ways to exploit this oversight:

1) Pokémon $00

The player can fill cartridge RAM with $00 bytes by pressing up+select+B on the title screen to clear save data. (This is important to do even if no "continue" option is present on the file select screen due to random data possibly existing in cartridge RAM.) After entering the Hall of Fame without saving beforehand, the player will have Pokémon boxes of entirely $00 bytes, notably missing the $FF byte initialization is supposed to place in the Pokémon list.

Inserting a Pokémon into a box using Move Pokémon w/o Mail will shift the Pokémon list by 1 until it reaches an $FF byte. Here an $FF byte doesn't exist until the end of the Hall of Fame data which is just after Pokémon box data, shifting the entire box by 1 before writing the Pokémon data.

Upon inserting a second Pokémon into an uninitialized box, the first Pokémon that was inserted will have a $00 byte shifted into species. It can be withdrawn from the PC then deposited to and withdrawn from the Pokémon Day Care to update its entry in the Pokémon list to $00 as well. A $00 byte in the Pokémon list leads to glitches such as the Celebi trick.

2) Duplicate key items

The above Pokémon $00 setup with a Togepi as the first Pokémon inserted into the box will have a SquirtBottle shifted onto its held item. A held key item leads to glitches such as the expanded items pack. If the player entered the Hall of Fame without using glitches or cheats, both a Togepi (egg) and SquirtBottle will be available for this setup.

3) Previous Pokémon

Clearing save data is only required when no terminator is desired and can be skipped to instead allow the player to access Pokémon box data from the existing save. This can be done to obtain multiple exclusive Pokémon such as starter Pokémon or to reunite with the player's team from the previous playthrough, but still requires the Hall of Fame to be entered without saving since a new game was selected.

Some notes:

All of my testing was done on the English version of Pokémon Gold. Everything should work on the English version of Pokémon Silver, I do not know if anything will work on other language releases, and everything does not work in the English version of Pokémon Crystal. Pokémon Crystal added code to the Hall of Fame save that initializes the save data if it was not previously erased.

For quick testing, the memory addresses $D9F6 and $D9F7 represent the backup map group and number, which are used for the return location of generic maps. Going to the second floor of a Pokémon Center and editing the values to $10 and $08 respectively will cause returning to the first floor to instead take you to the Hall of Fame.

I really love natural glitches like this (just enter the Hall of Fame without saving!) so let me know if you have any questions.

Thanks! ~Sally

I think I was aware of this at some point but forgot it. Thanks for posting about this! It's a very interesting technique. I guess most people won't use it because it takes a lot of time, but if you're desperate about not managing to do the Bad Cloning process, that's an alternative ^^

Aha, I looked through threads, but not youtube videos, to see if this had been posted yet.

Everything from my initial message was posted into the PSR Discord by gifvex on 29 Aug 2017. Some things about Sally's message, such as the specific mention about Togepi, signals to me this was very likely not just a coincidence. But Sally clearly did her own testing and did not wait 5+ months to document it, so the credit is still deserved, regardless.