Datapoints in pkm, and their continuity

[theSLAYER]

Section 1.0: Foreword
There are various datapoints that may or may not get carried forward.
Note: when I label a generation as gen (x), I'm referring to the games made in that gen.

More information will get added as we go along.

Section 2.0: The datapoints and their continuity
2.1: Species ID

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Gen 1: The Pokémon's internal index number differs from their Pokédex number. The index number is the value that is stored in the data. However, if you're using PKHeX to edit a Pokémon, you would not notice this discrepancy.
Gen 2: The Pokédex number is stored.
Gen 3: The Pokémon's internal index number differs from their Pokédex number. The index number is the value that is stored in the data. However, if you're using PKHeX to edit a Pokémon, you would not notice this discrepancy.
Gen 4: The Pokédex number is stored.
Gen 5: The Pokédex number is stored.
Gen 6: The Pokédex number is stored.
Gen 7: The Pokédex number is stored.
Gen 8: The Pokédex number is stored.

When the Pokémon is brought forward, it follows the format of data that is stored.
For example, if transfers between Gen 1 and Gen 2, conversion from Gen 1 internal index to Pokédex number and vice versa to take place. The usage of the game's conversion table allows the Time Capsule exploit to transfer glitch Pokémon to transform into proper species in Gen 2. Do note that Celebi was excluded from that table, so it is not possible to get a Gen 1 Glitch Pokémon to transform into Celebi using this exploit.

2.2: Form ID

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Gen 1: Alt forms weren't a thing in this generation.
Gen 2: While alt forms were a thing in this gen (Unown), the letter it possesses is determined by their DVs.
Gen 3: While various Pokémon can have alt forms, the form ID datapoint did not exist.
For Unown, the letter is possesses is determined by their PID. Deoxys' form is determined by what version Deoxys is presently in. Spinda's spots are not true form changes, and is also determined by their PID (this continues to be true up to and including Gen 5, and will not be mentioned again).
Gen 4: Introduction of the form ID datapoint. Unown transferred from Gen 3 will retain the correct letter.
Gen 5: Continued usage of the form ID datapoint.
Gen 6: Continued usage of the form ID datapoint. Mega evolutions are an alt form, but one cannot normally see them outside of battle. Spinda's spots are not true form changes, and is determined by their EC (this continues to be true past Gen 6, and will not be mentioned again).
Gen 7: Continued usage of the form ID datapoint. Mega evolutions are an alt form, but one cannot normally see them outside of battle.
Gen 8: Continued usage of the form ID datapoint.

Form ID datapoint is retained when transferred forward. (Mega evolutions sprites show up in HOME, even tho they aren't in SWSH)

2.3 Personality ID (PID)

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Gen 1: Datapoint does not exist.
Gen 2: Datapoint does not exist.
Gen 3: Introduction of the PID datapoint. Used to determine gender, determine ability, determine nature, determine shininess, used to determine Spinda's spots, used to determine Unown's letter, used to determine Wurmple's evolution, used to determine size, and used to determine if Mirage Island appears in RSE.
Gen 4: Used to determine gender, determine ability, determine nature, determine shininess, used partially to determine characteristic, used to determine Spinda's spots, used to determine Wurmple's evolution, used to determine size, and used to determine Pokéathlon performance changes in HGSS.|
Gen 5: Used to determine gender, determine ability, determine shininess, used partially to determine characteristic, used to determine Spinda's spots, and used to determine Wurmple's evolution.
Gen 6: Used to determine shininess.
Gen 7: Used to determine shininess.
Gen 8: Used to determine shininess.
 

There may be other uses of PID that is not discovered and documented.
When a PID is transferred from G3/4/5 into Pokemon Bank, the PID may undergo slight changes, to maintain shininess/unshininess (read more here, or section 2.4)

While not used to determine IVs, nor Height/Weight, due to the understanding of how the RNG works in certain gens (G3, G4, G8), the PID additional relationship to other stats, besides the ones mentioned above.
G3 and G4: RNG relationship linked PID to IVs
Gen 8: RNG relationship for those under overworld8 linked PID to IVs, HT/WT, EC.

2.4 Shininess

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Shininess is not a datapoint by itself. In various generations, it is determined by various means.
Gen 1: Shininess does not exist. (However the Pokémon's DVs may yield a shiny, when transferred up)
Gen 2: Determined by the DVs.
Gen 3: Determined by PID and TID+SID
Gen 4: Determined by PID and TID+SID
Gen 5: Determined by PID and TID+SID
Gen 6: Determined by PID and TID+SID
Gen 7: Determined by PID and Full Trainer ID
Gen 8: Determined by PID and Full Trainer ID

Shininess (or alternatively, the lack of shininess) is maintained via transfers.
Most notable:
VC Gen 1/VC Gen 2 -> Bank (technically Gen 7 format until transferred away again):
When the Pokémon is transferred up, it'll gain a random PID that would maintain its shiny/non-shiny status.
Gen 5 -> Bank (technically Gen 6 format until transferred away again):
Shiny yield before Gen 6 and shiny threshold after Gen 6 is different. This means there is a small chance for certain non-shiny PIDs to become shiny when transferred. To maintain the non-shininess of those PIDs, those PIDs flip their most significant bit. This is the only time PIDs change throughout transfers. The full explanation is documented here.

So far, there is only one instance where shiny/non-shiny status is not carried forward when transferred. This is due to bad programming of DV-shinines recognition in Transporter, from VC Gen 1/Gen 2 -> Bank. Documented here.
 

2.5 Gender

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Gen 1: While Nidoran-M and Nidoran-F exists, those are technically separate species in the Pokédex. Gender as we know today in Pokémon did not exist then.
Gen 2: Introduction of the Gender concept, though it is not its own datapoint. Determined by the Attack IV and compared to the gender ratio.
Gen 3: Continues to not be its own datapoint. Determined by the PID and compared to the gender ratio.
Gen 4: While it has its own datapoint now, it is still initially determined by the PID and compared to the gender ratio.
Gen 5: While it has its own datapoint, it is still initially determined by the PID and compared to the gender ratio.
Gen 6: It has its own datapoint, and is determined by comparing a random number to the gender ratio.
Gen 7: It has its own datapoint, and is determined by comparing a random number to the gender ratio.
Gen 8: It has its own datapoint, and is determined by comparing a random number to the gender ratio.

When a Pokémon is transferred, or evolves, it retains its gender.
The one exception happens prior to Gen 6: Because Azurill and Marill have different gender ratios, its gender can change upon evolution. This is because prior to Gen 6, gender was determined based on PID, and evolution doesn't change the PID. Documented in the trivia here.

2.6 Ability

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Reminder: Hidden Ability did not exist before Gen 5.

Section 2.6.1 Ability Index

Gen 1: Ability as a concept does not exist.
Gen 2: Ability as a concept does not exist.
Gen 3: Introduction of ability as a concept. It did not have its own datapoint. Ability index is obtained from the personainfo of the species, which is based on ability slot determined via PID.
[Thus unable to make stuff like Wonder Guard Sableye; you can't manipulate the ability index, only ability slot (1 or 2) via PID manipulation]
Gen 4: Ability index gained its own datapoint.
Gen 5: Continued usage of ability index as datapoint. Note: A Pokémon also gains a bitflag to signify they have a hidden ability. Documented here.
Gen 6: Continued usage of ability index as datapoint.
Gen 7: Continued usage of ability index as datapoint.
Gen 8: Continued usage of ability index as datapoint.

Section 2.6.2 Ability Slot

Gen 6: Added Ability Slot as datapoint. Governs Ability 1, Ability 2, and Hidden Ability.?
Gen 7: Continued usage of Ability Slot as datapoint.
Gen 8: Continued usage of Ability Slot as datapoint.

2.7 Nature

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Gen 1: Nature as a concept did not exist
Gen 2: Nature as a concept did not exist
Gen 3: Nature as a concept was introduced. Determined by their PID.
Gen 4: Nature as a concept was introduced. Determined by their PID.
Gen 5: Has its own datapoint.
Gen 6: Has its own datapoint.
Gen 7: Has its own datapoint.
Gen 8: Has its own datapoint.

As Virtual Console G1/2 Pokémon does not have Nature, they were assigned one when transferred up.
The Nature those entries were assigned depends on the EXP value they had prior to transfer.

2.8 Held Item

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Gen 1: Held item as a concept did not exist
Gen 2: Held items as a concept were introduced, and has its own datapoint. They used the unused datapoint catch rate from Gen 1 data structure, to maintain consistency. This means you could trade a Pokemon holding a particular item to Gen 1, and it'll still be holding the same item when traded back into Gen 2.

Some wild Pokemon (caught in Gen 1) will be holding items.

Gen 3: Has its own datapoint. The item IDs differs from Gen 2's ID listing.
Gen 4: Has its own datapoint. Item item IDs differs from Gen 2's and Gen 3's ID listing, and will become the standard moving forward.
Gen 5: Has its own datapoint.
Gen 6: Has its own datapoint.
Gen 7: Has its own datapoint.
Gen 8: Has its own datapoint.

Starting from Gen 4, held items are not carried forward when transferred forward.
(so only Time Capsule [technically] and Pal Park retains held item, any other transfers doesn't)
Item ID listing became standardized with the advent of Gen 4, with newer entries being added to the existing ID listing.

2.9 EXP and Level

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Section 2.9.1 Experience

Gen 1 to Gen 8: Experience has its own datapoint.

Pokemon do not contain data for their current level. Instead, they hold the datapoint known as experience. The games calculate the level (to be displayed in their menus) based on experience and their level-up type. Experience is brought forward based on transfer.

Section 2.9.2 Met Level

Gen 1: Met Level as a datapoint did not exist.
Gen 2: Met Level as a datapoint was only introduced and used in Crystal.
The datapoint does not exist in GS, but nothing overwrites it.

Thus, if a mon was traded from C to GS, it'll keep the data, as nothing overwrites the value in that location.
If a mon from C was traded to Gen 1, the data will be lost/removed.

Gen 3: Met level has its own datapoint.
Gen 4: Met level has its own datapoint. If a mon is obtained via Pal Park, the Met Level is changed to the level it arrived as.
Gen 5: Met level has its own datapoint. If a mon is obtained via Transfer Lab, the Met Level is changed to the level it arrived as.

Pokemon Transporter (Into Gen 6 and 7 format): Datapoint continues to exist. Any mon transferred in would have their Met Level changed to the level it arrived as.

Gen 6: Datapoint continues to exist.
Gen 7: Datapoint continues to exist.

GO Park: Transfers from Pokemon GO would depend the Power Up level of the mon in GO, rounded down to the nearest integer.

Gen 8: Datapoint continues to exist. Transfers from Pokemon Bank would keep their Met Level (the Met level prior from transferring into HOME). Transfers from Pokemon GO would depend the Power Up level of the mon in GO, rounded down to the nearest integer.

2.10 Language

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Gen 1: Datapoint does not exist in Gen 1.
Gen 2: Datapoint does not exist in Gen 2.
Gen 3: Datapoint was introduced in Gen 3.
Gen 4: Datapoint continues to exist.
Gen 5: Datapoint continues to exist.
Gen 6: Datapoint continues to exist.
Gen 7: Datapoint continues to exist.
Gen 8: Datapoint continues to exist.

Starting from Gen 3, the value for the datapoint would continue to be carried forward during transfers.
There's a few things one may be interested in, if reading this section:

• For retail carts, European languages on Gen 1 can communicate and trade with each other, but the game doesn't differentiate between which original language the mon came from.
• For both retail and VC, European languages of G1/G2 cannot communicate with Japanese G1/G2.
• For retail, European languages of G1/G2 can communicate with Korean G2, provided the names used for the mons don't lead to any kind of communication errors or issues. This does not apply to VC copies (VC KOR G2 cannot communicate with VC European G1/G2).
• For VC -> Pokemon Transporter, the language assigned is based on the VC game it was transferred from, not the language of the game it originated from.
  
  For example: SPA Pikachu traded to ENG Yellow. Then that Pikachu was Transported up into Bank.
  The language it'll have is ENG (the game it was transported from), not SPA (the game it originated from).
   
• As mentioned, as a language datapoint does not exist in G1/G2, the usage of Time Capsule have absolutely no effect on language.
• While not popularized, G3 can trade and battle with other G3 games of any language. However, any non-Japanese mon in JPN games might appear a bit different, due to character limit for names.
  Any Japanese character set may also appear off in non-Japanese G3, due to differences in character encoding table.
• KOR G4 copies cannot communicate with non-KOR G4 copies. This is because Korean version of the Pokemon games were only allowed to exist after foreign importing/exporting laws [citation needed] were lifted. So by that time, non-KOR G4 games were already produced, with the lack of Korean characters in their character table. This would not be an issue G5 onwards.
• Because there are no KOR copies of G3, KOR G4 Pal Park works on any languaged version of the G3 games.
• Along the same note of the above point, Non-KOR G4 games can only communicate with G3 of the same language (for Pal Park).
• A Japanese Slot-2 Distribution cart cannot be used on non-Japanese G4 games.
• There is no language restriction for using other languaged G3 carts for Dual-Slot/Dongle method.
• Poke Transfer, the transfer feature for G4->G5, only works for cartridges of the same versions.
  The mons within can be of different languages, however.
• Along the same note as the above point, the Relocator, which can certain special events from G4->G5, is restricted by the same language cartridge limitation.
• The language of the mon obtained from the GO Park (in LGPE) depends on the language set for that playthrough of LGPE.
• The language of the mon obtained from the GO Transporter (in HOME) depends on the language initially set in first use of the mobile version of Pokemon HOME.

2.11 Region, Sub-Region and Country

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G1 - G5: These datapoints does not exist
Gen 6: Introduced in G6.
Gen 7: Continues to exist in G7 (except for LGPE).
Gen 8: Datapoints cease to exist in G8. The data is wiped.

Poke Transporter: Regardless if the mon is transferred from G5, or from VC G1/G2, the assigned values are based on the Transporter's 3DS settings.

2.12 Height and Weight

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G1 - G6: These datapoints does not exist.
G7: These datapoints were introduced in LGPE (So they don't exist in SM USUM)
G8: These datapoints continues to exist, even if they are apparently not visibly used in SWSH.

Transfer Details:
LGPE: Mons caught or in-game traded get assigned a value.
SWSH: Mons caught or hatched or in-game traded or Mystery gifted get assigned a value.
GO -> LGPE: The height and weight appears to be the same as the GO one.
LGPE <-> HOME or SWSH<-> HOME: The original value is retained (when applicable).
GO -> HOME: The GO's HT/WT is not retained. They are reset to the species' default value.
Bank -> HOME: No value assigned. They'll be 0.
HOME (Mystery Gift): No value assigned. They'll be 0.

As RNG for certain Gen 8 mons are understood, RNG relationship for those under overworld8 linked PID to IVs, HT/WT, EC.

2.13 Origin Game

2.14 Battle Version

2.15 Met Location

2.16 Met Date

2.17 Met Level

2.18 Egg Location

2.19 Egg Date

2.20 Met Poké Ball

2.21 Fateful Encounter

2.22 HOME Tracker

2.23 IVs / DVs

2.24 EVs

2.25 Dynamax Level

2.26 Gigantamax Factor

2.27 Current Moves

2.28 Egg Moves

2.29 Technical Records

2.30 Trainer Information (OT, TID, SID, OT Gender)

2.31 Latest (NotOT) Handler Information (OT, OT Gender, OT Language)

2.32 Current Handler [The Green box]

2.33 Encryption Constant

 

Construction notes: I have other commitments in real life. I'll continue when I want to continue.