Pokémon HeartGold and SoulSilver

Pokémon HeartGold and SoulSilver Versions are remakes of the original Pokémon Gold and Silver Versions.

Attacks 468-470
When taught to a Pokémon, data about unused attacks 468, 469 and 470 does not necessarily freeze the game. Such attacks are special, have a power and accuracy of 100 and a PP of 10. Other invalid attacks do not give this data and simply freeze the game as soon as they are recalled, perhaps suggesting that the move database was once intended to end at 470 as a nice round figure rather than 467 (Shadow Force).

Leftover Content
Files originally found in Pokémon Diamond and Pearl have found their way into HG and SS. On the other hand, Platinum related sprites are noticeably missing.

Item Bag
The sprites for the D/P male hero's item pocket selection's upper screen remain. Missing are the female hero's purse and Platinum's white bags.

Overworld sprites
Several overworld sprites were not reintroduced in HeartGold and SoulSilver but still exist within the game such as the associated data for the playable male and female characters (as they appeared in Diamond and Pearl) including their 'berry planting' poses and Gym Leaders (with the exception of Maylene and Crasher Wake, who appear in Celadon).

Slot machines
Most graphics from the D/P slots game remain, including the Clefairy bonus mode. The slots had a design overhaul in Japan, but were replaced by a Voltorb Flip minigame for everyone else.

Leftover Game Corner map
In NTSC-US and EUR localizations of the Pokémon HeartGold and SoulSilver, although the original Game Corner map from the Japanese version is no longer accessible in normal gameplay, it still remains within the game code and has a hexadecimal identifier of. As in the Japanese versions, a TM78 Captivate can be obtained in the original Game Corner map. However, the dialogue for NPCs in this map has presumably been deleted, because speaking to any of the remaining NPCs gives only 'blank' text on the top screen. Coins and items from the Game Corner can still be purchased as normal, with visible text on the touch screen. Activating any of the slot machines will initiate the Voltorb Flip minigame.

The Underground
There's a bunch of files related to the huge underground complex found in the three earlier Pokémon DS games. Most (if not all) of the 2D graphics remain, including the traps, radar pinging, and the mining mini-game. It's a possibility that it was going to be remade, being that the walking sprites for both the D/P heroes exist with the other underground files; Platinum's heroes are missing.

Lost Debug Mode
Nearly 2,000 text strings can be found talking about changing values for unknown debugging features. However, the debug menu code is probably lost. This debug mode is apparently based on the one in Pokémon Platinum, containing references to events such as the Distortion World; it seems more of it survives than in that game.

To see the debug mode strings, please look at the notes.

Lock Capsule
This unreleased event item, intended to be transferred to Black and White to unlock an event there, can be added to the Bag through hacking. Since its only intended purpose is to be transferred to another game, it does absolutely nothing in HeartGold and SoulSilver. However, the Relocator in Black and White will not recognize the item, and therefore will not relocate it, most likely due to the event being cancelled. Because of this, the Lock Capsule is completely useless in HeartGold and SoulSilver.

None
If a Mystery Gift item is forced but the item identifier is of 00 (no item), when the item is retrieved from a PokéMart, the game will state that the player has received the gift "None", this is presumably just an error handler if the game developers or Nintendo were to accidentally refer to an item name in game but not specify its identifier.

Route 23
Route 23, the huge route on which Victory Road is situated in Pokémon Red and Blue and Pokémon FireRed and LeafGreen, is unceremoniously replaced by a larger guard house in both the original Pokémon Gold and Silver and their remakes. However, a small stretch leading from the northern exit of Victory Road to the Pokémon League's front door is still identified within Pokémon Gold and Silver as Route 23; in HeartGold and SoulSilver, this stretch is identified as the Indigo Plateau, as it is in the Generation I games and their remakes. Despite that, the location data for Route 23 still exists in these games.

Unused Items

 * Photo Album: "A nice photo album for storing all the photos taken along your adventure." In the final version, photos are stored on your PC instead.
 * Slowpoke Tail: "A very tasty tail of something. It sells for a high price." Existed in the original Gold and Silver. It has been upgraded to a key item, but ends up unused.
 * Blank item data occupying 21 identifiers exists in between identifier (Griseous Orb) and  (Adamant Orb). These are perfectly formatted items which do not crash the game, unlike invalid items; using the error handler "???" as a name and a ? symbol as the picture, suggesting that they may have once been items from Diamond and Pearl, when they were still in development.

Sinjoh Ruins Return Trip
As is well known, the Arceus distributed at Japanese movie theatres and at Toys 'R Us can enable the player to enter an area called the Sinjoh Ruins and choose between a level 1 Dialga, Palkia, or Giratina, all holding their signature items.

What is less well known is that the unused Hall of Origin event Arceus within Diamond, Pearl, and Platinum can, if obtained through a hacked Azure Flute or a warp to the Hall, enable a second trip to the Sinjoh Ruins, where the Hiker in the cabin has some different dialog and it is possible to choose one of the dragons that you did not choose the first time (complete with the really creepy cutscene). There is no way to obtain the last dragon whatsoever.

The Hiker in the cabin's special return-trip dialogue: Well, hello! We meet again! Cynthia has gone back to Sinnoh. She is the Sinnoh League Champion. She studies various ruins despite her tight schedule. How wonderful she is!

Arceus ???-type
Arceus' ???-type form from previous games makes its final appearance here, as Pokémon Black and White would take out the ???-type entirely.

Unobtainable Shiny Pokémon
For the sake of consistency, every Pokémon in every Pokémon game is given a Shiny variant. Most Shiny Pokémon have been obtainable through random chance encounters or event distributions, including most Legendary Pokémon. However, a few Pokémon cannot be obtained in this form without hacking, and as a consequence, normal players would never be able to see their Shiny coloration.

Arceus


Arceus has a Shiny palette for each of its 18 forms, including the unused ???-type (see above). However, because the only way to obtain it legitimately was through distributions, the Shiny version of Arceus was left unobtainable through normal means.

Spiky-eared Pichu


The Spiky-eared Pichu from the special Ilex Forest event (unlocked via the Shiny Pichu distribution) has a Shiny palette as well. However, it cannot be obtained as Shiny from the event.

Head Smash Nosepass
Nosepass gained the ability to learn Head Smash as an egg move in these games. Normally, that wouldn't be notable, because everyone and their mother gained the ability to learn Head Smash as an egg move in these games.

Except Nosepass can't breed with anything that learns Head Smash, making the move unobtainable. Oops!

The ability was removed in Pokémon Black and White.

Voltorb Flip
In all non-Japanese versions of the game, the traditional slot machines were replaced with a Minesweeper/Sudoku hybrid called Voltorb Flip. Japan was the only region that got the slot machines. BOOOOOOOOOOOOOOOOOOOOOOOO!

Anti-Piracy
MD0M9wM6_Vo If the game detects it is being played on a flash card or emulator, it will freeze at the start of a battle with the player's Poké Balls constantly spinning. Most emulators are able to avoid triggering this.

Unused Textures
There is an unused texture within the 41st tileset in the game, which simply spells "YoBi." When translated, it simply means, "preliminary."

There is also a second unused texture, which has the word "gym" on it. It's a placeholder graphic for a placeholder model.

Obsolete references to Gold/Silver/Crystal features
There are a handful of references in the game's dialog to features that were present in the original Gold/Silver/Crystal, but are either no longer present or have been altered in such a way that the references are no longer relevant.


 * Kurt in Azalea Town still refers to "Poké Ball" in the singular form in most of his dialog. In Gold and Silver, he would only turn one Apricorn at a time into a Poké Ball for the player, whereas in HG/SS the player can give him multiple Apricorns at a time and receive multiple Poké Balls, making his speech slightly awkward.
 * A poster on the first floor of the Goldenrod Radio Tower advertises the "Lucky Channel." This was the radio show in G/S/C that would broadcast lottery numbers which, if they matched the Trainer ID of any of the player's Pokémon, would allow them to win prizes. The show is no longer broadcast in HG/SS, having been replaced by Felicity the lottery attendant behind the counter at the radio tower, who tells the player the daily lotto number when spoken to.