theSLAYER

A patent was found online, and it supposedly describes how HOME operates. What we’ve understood of HOME so far appears to match the details. If you’re interested, take a read: 

Credits to xfire for finding this.

When transferring between games, data in other children substructures get initialized mostly based on the initial child substructure.
Here is a quick rundown of the various children substructures and entry from which games would initialize them first. (assuming all transfers are legitimate)

Example:
A Darkrai, game of origin GO, would first populate the SWSH child, when entered from GO.

So, let's say you're trying to insert the file into your BDSP/PLA. If it didn't have a suitable HOME tracker, the SWSH child would never be populated, and that'll result in an illegal Darkrai if you try to transfer it to a different game.
Even before transferring to other games, you can tell that it's illegal when viewing HOME either in Switch (game accessed HOME/SWSH) or mobile.

On Switch (HOME or SWSH access)

The G Symbol (as seen on the Darkrai to its left) is missing. It should only be missing for GO entries sent to LGPE.
Should not be missing for direct GO -> HOME entries.

On Mobile

The ball is notably missing. It should not be missing.

How to remove background from a Pokédex/in-game video capture (after the video was turned into a gif):
https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228819

You may have to cycle through the "white background" process a few times to remove all the blips and leftover dots from the background.

If the model itself has colors removed, you may have to reduce the fuzziness, and go through the process multiple times. If the model is still affected, you may need to take the clean gif, and use Split: Gif to sprite sheet and add back the affected colors in. (For example, I did that with Zekrom's tail above)

Note: I attempted to perform transparency color corrections on Eternatus and Snom, based on Pkparaiso's old gifs that showcased transparency but the color is wrong. It appears they have since switch to opaque coloration.

Sources:
Kalaxe:
https://projectpokemon.org/home/forums/topic/48971-sprites-pokemon-sword-shield/?do=findComment&comment=239383

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Credits found here:
https://projectpokemon.org/home/docs/spriteindex_148/3d-models-generation-1-pokémon-r90/?do=findComment&comment=1163

Sources:
Main Bulk of images:
https://www.pkparaiso.com/xy/sprites_pokemon.php
https://www.pkparaiso.com/xy/sprites_pokemon_espalda.php
https://www.pkparaiso.com/xy/sprites_pokemon_variocolores.php
https://www.pkparaiso.com/xy/sprites_pokemon_variocolores_espalda.php
https://www.pkparaiso.com/rubi-omega-zafiro-alfa/sprites_pokemon.php
https://www.pkparaiso.com/rubi-omega-zafiro-alfa/sprites_pokemon_espalda.php
https://www.pkparaiso.com/rubi-omega-zafiro-alfa/sprites_pokemon_variocolores.php
https://www.pkparaiso.com/rubi-omega-zafiro-alfa/sprites_pokemon_variocolores_espalda.php
https://www.pkparaiso.com/sol-luna/sprites_pokemon.php
https://www.pkparaiso.com/ultra-sol-ultra-luna/sprites_pokemon_sin_bordes.php

Cleaning Efforts:
theSLAYER:
Pheromosa Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=219173
Dawn Wings Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224605
Marshadow Front Scream Animation - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228819
Marshadow Shiny Front Attack Animation - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228821
Transparency related issues (these are just examples, not all is in this post) - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228858

BlackShark:
Celebi Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=218742
Shiny Celebi Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=218760
Partner Cap Pikachu Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224264

Wratih89:
Cresselia Front -https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=219196

Andrewism:
Scizor Front, Scizor-F Front, Mega Scizor Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=222057
Shiny Scizor Front, Shiny Scizor-F Front, Shiny Mega Scizor Front, Scyther Front, Scyther-F Front, Shiny Scyther Front, Shiny Scyther-F Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=222097

parsath:
Naganadel Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224597
Shiny Naganadel Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224607
Shiny Poipole Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224610
Poipole Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224615

Lessangel:
Ultra-Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224598
Shiny Ultra-Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224600
Shiny Stakataka Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224602
Shiny Dawn Wings Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224603
Shiny Dusk Mane Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224604
Shiny Dusk Lycanroc Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224608
Shiny Blacaphalon Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224609
Shiny Zeraora Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224611
Blacephalon Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224613
Dusk Lycanroc Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224614
Dusk Mane Necrozma Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224616
Stakataka Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224617
Zeraora Front - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=224618
Ultra Necrozma Back - https://projectpokemon.org/home/forums/topic/42637-help-finding-usum-animated-sprites/?do=findComment&comment=226327
Dusk Mane Necrozma Back (Regular and Shiny), Dawn Wings Necrozma Back (Regular and Shiny), Ultra Necrozma Back (Regular and Shiny), Poipole Back (Regular and Shiny), Naganadel Back (Regular and Shiny) - https://projectpokemon.org/home/forums/topic/42637-help-finding-usum-animated-sprites/?do=findComment&comment=226329
Dusk Lycanroc Back (Regular and Shiny), Stakataka Back (Regular and Shiny), Blacephalon Back (Regular and Shiny), Zeraora Back (Regular and Shiny) - https://projectpokemon.org/home/forums/topic/42637-help-finding-usum-animated-sprites/?do=findComment&comment=226366
Ash CaP Pikachu Back (Original, Hoenn, Sinnoh, Unova, Kalos, Alola, Partner) - https://projectpokemon.org/home/forums/topic/42637-help-finding-usum-animated-sprites/?do=findComment&comment=226368
(Kalaxe compiled, but Lessangel did the cleaning) Alola Shiny Backsprites, Furfrou Trim, Genesect Forms, Kyurem Forms, Various Cosplay Pikachu, Pokemon Totems, Arceus Back Shiny (Various), Unown (Various), Certain missing backsprites - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=227180 (the mega link)

Kalaxe:
Pheromosa Back - https://projectpokemon.org/home/forums/topic/41471-volunteers-needed-with-cleaning-animated-gifs-for-event-gallery/?do=findComment&comment=227825
Glameow (Gen 7) - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228697
Missing Genders Back - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228842

Andrew1207:
Marshadow Shiny Front Scream Animation - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=228820

Azkuonmo:
Druddigon Back (Shading Correction) - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=230921

Ellicrum:
Reshiram (Front and Back) Attack Animation - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=231734
Some other transparency related sprites - https://projectpokemon.org/home/forums/topic/43730-help-removing-background-of-3ds-sprites-are-missing/?do=findComment&comment=231800
 

And anyone else that I may have forgotten to mention, thank you. If you want to be credited, leave a link to your post (containing the contribution) in the comments here :3

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Sprites from Prototype RG (credits to HelixChamber)

Spaceworld 99 (GS beta)

SWSH Part 4

Spoiler

SWSH Part 3

Spoiler

SWSH Part 2

Spoiler

SWSH Part 1

Spoiler

Spaceworld97 (GS demo)

Spoiler

Non-shiny SW97 sprites	Shiny SW97 sprites

 

 

Note: It's not an error. Presently, HOME is programmed to display that ball for Eternal Flower Floette, though it's 3D Model still exists (by the mobile version).
 

We have a support and contribution page here: