Atrius97

I've removed your link. Please do not offer Scarlet and Violet savefiles. Sharing seeds is fine, but Legends: Arceus introduced savefile verification and it may not be safe to use publicly uploaded Scarlet and Violet saves.

I'm not familiar with ACE/glitch pokemon, but you could open the savefile in PKHeX and compare to a legal copy of the GF Mew from the Mystery Gift Database.

There is likely still some values that are being flagged. I can confirm that the GF VC event Mew are not blocked, there have been no updates to Pokémon Bank/Transporter of that nature.

All three are Faraway Island Mew from Japanese Emerald. There's no "difference" between them other than the trainer name, they're not from different events. The name depends on the person who caught them.

Unless you know a way to magically restore 40% of the savefile that is completely empty, no.
Load the backup save, or an older manual backup.

11 hours ago, MIO1339 said:

I don't know why this Murkrow always say "Encounter Type PID mismatch" even the seed are correct
If I know Murkrow belong to the shadow pokemon that can be shiny I don't know why this can't?

Several Pokémon in Colo and XD use their own specific generation method, not the standard XD/Colo method. In Pokefinder, under "Method", select Colo from the dropdown, and then under "Shadow" select Murkrow, Gligar, or Heracross.

Depending on the hack, some ROM hack creators have a custom fork to support their specific version of the game. PKHeX is open source, and if the devs want to, they're welcome to make a compatible build of PKHeX.

The point of knowing the seed is so you can inject it yourself. The top half of the PID won't match your trainer id and secret id if someone shared a file and you tried to match it to your trainer data, it would cause PID mismatch.

This issue only occurs in the latest stable release of PKHeX. Until an update is made that fixes it, you can use the previous stable release by going to this page:

Then scroll down to "See changelog", select 22.12.18 from the dropdown, then click the small "Download" link below the old Version 22.12.18 changelog.

No. You can either connect online ingame and have them automatically update to the latest Poke Portal News, or you can import the blocks from a different Poke Portal News event. 
Here are the blocks for "no event"

PKHeX is open source, there are no settings to allow different savefile sizes/ROM hack support, but you're welcome to edit the program and create your own version of PKHeX that has support for a specific hack.

https://github.com/kwsch/PKHeX

In Pokémon Colosseum, only Shadow Pokémon can be shiny, and everything else encountered in Colosseum is prevented from being shiny.

In Pokémon XD, the reverse is true. Only non-shadow Pokémon can be shiny, and all Shadow Pokémon are prevented from being shiny.

Lugia is a Shadow Pokemon in XD, and therefore cannot be shiny.

I'm not psychic. You have to upload the save before anyone can guess at whether it contains any salvageable data. 

If you lost access Violet because you uninstalled it, and you cannot connect to the eshop in stock firmware (connection issues or because you're banned), there's nothing you can do to regain access to Violet without purchasing a physical cart.

That aside, you should be able to move your savefile via local transfer

https://en-americas-support.nintendo.com/app/answers/detail/a_id/45047/~/how-to-transfer-your-save-data-to-a-nearby-nintendo-switch-system

You would have to extract the savefile using a savefile manager, not just uploading files from your SD card.
https://projectpokemon.org/home/tutorials/save-editing/managing-3ds-saves/

If you want them all to have unique nicknames, then no, there isn't a way to do it "all at once". Even writing a batch command that sets each nickname in sequence would take roughly as long as naming them all by hand, but if you did want to do that, you can sequence commands by adding an extra line and ; in between. Example below:

=Box=1
=Slot=3
.Nickname=John
;
=Box=1
=Slot=4
.Nickname=Steve
;
=Box=1
=Slot=5
.Nickname=Mark

The "returning (Pokemon) to (name of the trainer)" message no longer exists in Scarlet and Violet. Even if all the trainer details match, it still doesn't display that message when trading someone's pokemon back to them.

The reason that Pokémon traded in Scarlet and Violet refuse to obey, even if they match the original trainer, is because Scarlet and Violet have an additional preventative measure. They track the "met level" for the original trainer, but they also track the level that the "previous non-original trainer" had that pokemon as.

This means that if you catch a Pokemon at level 5, and level it up yourself, it will obey you even if it surpasses the number of badges you have, but if you catch a Pokemon at level 5, trade it to your friend, and have them level it up instead, when traded back to you it will disobey until you have the required number of badges.

This feature is unfortunately triggered even if you overlevel a pokemon yourself, trade it to someone, and immediately trade back. There is no way around this feature, you will not be able to trade people high level pokemon that obey them if they do not have the required badges, even if all the trainer details match.

It is possible, and it will be determined when the Encryption Constant is generated when moved via Transporter to Pokémon Bank, as Gen 1/2 do not have PID or EC.
Since those are generated randomly, it would be the standard odds, 1/100 to have an EC where "EC mod 100 == 0" which results in Three Segment.

You could transfer hundreds of them to attempt to have one be assigned the correct EC, either legitimately or via cloning glitches in Gen 2 to make hundreds of copies, or do Transporter RNG abuse to attempt to force one to have the correct EC.
https://www.pokemonrng.com/transporter

All 3DS and 2DS models are hackable, regardless of the system firmware version, you are mistaken that your updated 3DS "can't run Homebrew anymore". 

https://3ds.hacks.guide/

Tera Raid Pokémon have a PIDIV correlation, you cannot alter their IVs, PID, EC, Nature, etc. without calculation an entire set of valid stats.
See these threads for more info:

Correct. With a custom firmware 3DS you're limited to games/encounters in Gen 7 (3DS) and earlier, but with a modified Switch you would have access to Gen 7 (Switch) through Gen 9 encounters.

There is a short list of Legendaries and Mythicals that can exist at low levels, and be Shiny, prior to Pokémon Go/Gen 8.

Level minimum of 30 and can be Shiny:

Quote

Mew, Japanese Emerald, Faraway Island
Raikou, Entei, Suicune GAMESTP events for Gen 4 (always shiny)
Virtual Console Crystal Celebi
Regirock, Regice, Registeel from Platinum
Latios and Latias from ORAS
Deoxys from FRLG or Non-Japanese Emerald, Birth Island
Shaymin from Platinum, Flower Paradise

Level minimum of 5 and can be Shiny:

Quote

Jirachi from Colosseum Bonus Disc, or Channel

Level minimum of 1 and can be Shiny:

Quote

Dialga, Palkia, and Giratina from HGSS Sinjoh Ruins event
Regigigas from Platinum, Snowpoint Temple
Manaphy from Ranger Egg in Gen 4, (requires a second game to hatch the egg via TSV abuse, original save that receives the egg cannot hatch it as shiny due to a partially functioning shiny lock)
Phione, bred from Manaphy in any game

Yes, what you want to do is safe to do online.

If those are the only things you intend to do, I have a few recommendations:

If you are having your personal OLED modded by someone else, please ask that they install no NSPs, Tinfoil, XCIs, and no emunand, as all are potential ban risks and you don't need any of them. Ask for the bare minimum required, ie Hekate and Atmosphere.

If you are buying a "premodded one", obtain proof that it has access to the eshop and online services and is not already banned. When it arrives, boot it into stock and before connecting it online, perform a full factory reset, and completely reformat the SD card to FAT32, as most sellers tend to load the console with a ton of bloat like "lots of free (pirated) games" which can get you banned, and bundled software you don't want or need.

If you have to do the latter, you will want to install custom firmware on your own at that point, from scratch. If the process is generally the same as installing custom firmware for non-hard modded consoles, you can follow this guide: 
https://nh-server.github.io/switch-guide/user_guide/sysnand/sd_preparation/

A: The first half of the PID would need to be altered to cause it to be shiny for your Trainer ID and Secret ID.
This post explains a bit more in detail:

B: You haven't set the Height, Weight, or Scale for that Indeedee, as RaidCalc does not display those values (at least not yet, you're welcome to make a feature request). You also forgot to set the EC or Encryption Constant.

You could either use Tera-Finder to see the full details of that seed including Height, Weight, Scale, etc and set the correct PID, or you could inject that seed and complete the raid ingame. Either works.

https://github.com/Manu098vm/Tera-Finder/releases