Bad clone glitch: Difference between revisions
→Obtaining a bad clone: Added a new section about whether it is possible to create useful bad clones on a save file, and adjusted the procedure.
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{{Major glitches}}
{{PRAMA|bad-clone-trick}}
The '''bad clone glitch''' is a [[natural glitch]] in {{GSC}} that allows the player to obtain
Broadly speaking, the term "bad clone" includes two kinds of glitch Pokémon:
* A "real" bad clone, which is an [[unstable hybrid Pokémon]]. Such a bad clone can be stabilized into a [[?????]], enabling many other glitches such as [[????? party overloading]] or [[Time Capsule exploit]]. It also has an unterminated nickname, and thus can usually be used as a "friendly clone" if desired, although the timing window for getting a "real" bad clone is usually much tighter than that for getting a "friendly clone".
* A "friendly clone" (a term from the speedrunning community<ref>[https://www.speedrun.com/pkmncrystal/guide/axd5j Pokémon Crystal any% guide] by entrpntr</ref>), which is normal in every aspect except for its [[Unterminated name Pokémon (Generation II)|unterminated nickname]]. There is no known way to exploit a "friendly clone" in Gold/Silver, mainly due to stricter error checking for nicknames in those versions. However, in Crystal, a "friendly clone" can either be exploited for [[0x1500 control code arbitrary code execution]], or for simple buffer overflow (which can give the player a "real" bad clone).
Generally, a "real" bad clone is more exploitable, but also much more difficult to obtain. Technically there are other possible kinds of bad clones, such as one with correct species bytes but no moves<ref>[https://pokemon-speedrunning.github.io/speedrun-routes/#/gen-2/gold-silver/main-any/silver-no-collision-route/ Pokemon Silver Any% No Collision Route]</ref>, although they are even more unlikely to appear. The bad clone glitch can also be used to create unstable hybrids between valid Pokémon, but such unstable hybrids are not known to be game-breaking in any way.
==Obtaining a bad clone==
=== Requirements ===
Not all save files can produce "useful" bad clones (unstable hybrids with ????? (hex 00) and/or unterminated name Pokémon). To produce "useful" bad clones:
* It is ideal if the player has used the in-game clear save data feature (Select + Up + B) at least once since owning the game cartridge (otherwise, it may be unpredictable whether "useful" bad clones could be produced).
* There must be at least one box that has never been full at any point.
* The player should not use a save file edited by PKHex ''if the goal is to create an unterminated name Pokémon''.
{{Explanation|contents=
The bad clone glitch relies on unused data in the SRAM, namely the section of box data that corresponds to empty slots in the box (e.g. if a box currently contains 10 Pokémon, then slots 11–20 are empty).
* Since the relevant sections of data are not initialized when creating a new save file, the contents of SRAM ''before'' creating the save file affects possible results of the bad clone glitch.
** The in-game clear save data feature zeros out all of the SRAM data, which guarantees that "useful" bad clones can be produced.
** If the SRAM is ''never'' initialized, then its contents are unpredictable on real hardware, and handled differently by different emulators.
* When a Pokémon is removed from a box, all data after its slot are shifted to the front, but the data in slot 20 is left as is (even when Pokémon 20 itself is removed, it is just its first species byte that is overwritten by the $FF party terminator, leaving most of its data intact). Therefore, if a box ''has ever been full'', even if it is emptied later, all data in unused regions will be copies of the last Pokémon in slot 20, preventing the box from producing "useful" bad clones.
* When a save file is edited with PKHex, upon exporting the save, PKHex will fill all currently unused OT name and nickname data of all boxes with text terminators, making it impossible to obtain a bad clone with an unterminated name.
}}
=== Procedure ===
{{researchneeded|Verify the reset timings.}}
# Deposit at least one Pokémon in a box.
#* To obtain a "useful" bad clone, the box must never have been full, and the number of Pokémon in the box after depositing must be larger than the number of Pokémon in the box in the current save file. (If either condition is not satisfied, then the glitch will only produce unstable hybrids between valid Pokémon.)
#* The more Pokémon there are in the box after depositing, the larger the timing window, and thus the more likely the glitch will succeed. However, to avoid completely filling the box by accident, it may be ideal to just use 15–18 Pokémon.
* Shortly after the Yes/No box disappears (Gold/Silver)▼
# Change boxes and reset the game at the following exact timing:
* After SAVING... DON'T TURN OFF THE POWER. is fully printed (Crystal)▼
▲#* Shortly after the Yes/No box disappears (Gold/Silver)
▲#* After SAVING... DON'T TURN OFF THE POWER. is fully printed (Crystal)
If the Pokémon was not cloned, the reset was too early, and the player can deposit another Pokémon and try again. If the Pokémon was cloned successfully ("good" clone), the reset was too late, and the player should release the clone, save the game, and then deposit a Pokémon and try again.
To identify a bad clone, the bad clone may be female with a glitched name and become level 1 after you withdraw it from the PC. Contrary to the belief of some, if the original Pokémon was female it is still possible for the bad clone to be female (not male), although it is a good idea to use a male Pokémon in order to more easily identify a bad clone in case there are other male Pokémon in the box.▼
==== On the Game Boy Player ====
Notice that on the Game Boy Player (common for speedruns), the [[reset fadeout delay]] applies, so the timing to press the reset button is different:
* Immediately after pressing A on "Yes" (Gold/Silver)
* After the second "F" in "SAVING ... DON'T TURN OF'''F''' THE POWER." (Crystal)
==== On Pokémon Stadium 2 ====
==== On emulators ====
Another way to get a bad clone in BGB emulator in English Pokémon Gold, Crystal is to do it with five Pokémon deposited into box 4, set a breakpoint for de=AD6D (Gold) or de=AD11 (Crystal), advance the execution flow with F7 and then reset the game.▼
On advanced emulators that support instruction-level breakpoints (such as BGB), the player can use breakpoints to help time the reset.
▲
▲To identify a bad clone, the bad clone may be female with a glitched name and become level 1 after you withdraw it from the PC. Contrary to the belief of some, if the original Pokémon was female it is still possible for the bad clone to be female (not male), although it is a good idea to use a male Pokémon in order to more easily identify a bad clone in case there are other male Pokémon in the box.
==== Alternative method with different reset timing ====
In the above method, the player triggers a game save by changing boxes (which is necessary in the [[Pokémon cloning (Generation II)|normal cloning glitch]] for a relatively large timing window), and then interrupts the save by resetting. In fact, for the bad clone glitch, the player can also trigger the save through the "Move Pokémon w/o mail" feature (or presumably through saving manually in the Start menu), instead of changing boxes.
An important difference is that, when using this method, the player should reset after "SAVING... DON'T TURN OFF THE POWER." is fully printed, regardless of whether the game is Gold/Silver or Crystal. The length of the timing window should remain the same as the original method in theory, although it has been reported that in specific cases (namely, German Gold on VC), this method seems to work much better than the original method (the original method seems to always fail, whereas this method seems to have a "standard" chance of success).
==Properties of the bad clone==
A "real" bad clone is an [[unstable hybrid Pokémon|unstable hybrid]] between the cloned Pokémon and a ????? (hex 00). It is sometimes referred to as a glitched version of the original Pokémon; for example, a "glitched Sneasel".
The bad clone will usually have a nickname with a large amount of [[glitch text]] in Pokémon Crystal. It usually is female and level 0 in the PC, but will become level 1 after you withdraw it. It usually has no moves, but sometimes may have glitched moves, and on rare occasions cannot be withdrawn from the PC {{clarify}}.
In Pokémon Gold and Silver, the bad clone's name should appear blank. In Pokémon Crystal, the high amount of glitch text may be problematic, and could cause a crash. This is because in Gold and Silver, Null characters simply cause the function PlaceString to exit, whereas in Crystal, for some reason a change was made to PlaceString in which a question mark is printed to the screen upon reading a null char, and the function will continue to read characters. To avoid crashing from this, you can use a potion to open the Pokémon menu (without actually using the potion) to put a 0x50 terminator farther into wStringBuffer1, which should make the bad clone's name safe to view in the box.
==Explanation==
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===Unterminated name exploits===
{{main|Unterminated name Pokémon (Generation II)}}
Bad clones with unterminated names can also be used for various other exploits, notably [[0x1500 control code arbitrary code execution]].
== References ==
<references />
[[Category:Generation II glitches]]
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