theSLAYER

Assuming that you’re just transferring the backed up data back to the same exact 3DS unit, and no system reset/transfer has been done to it: you could try to delete secure value after you’ve placed the contents back into the main SD card. Do not boot the games before deleting the secure value. In the future, use a save manager (like Checkpoint or JKSM) to create save backups.

Export current block, then use a hex editor to edit the exported file. Once you’re done, import back into your save, then export the edited save.

Some bots can ignore the legality check. Anyhow, wait for PKHeX to update to latest, or place the wc8 files in the mgdb folder (have that folder in the root of PKHeX folder)

I’m assuming the fashion blocks didn’t change between game revisions. that would mean you imported the wrong file into the wrong block key. check the fashion blocks page under downloads/saves. It should have steps there.

If you're looking into information for shiny mythicals:

Because that feature is planned for but not fleshed out. It isn't available right now.

Shiny Mew for Crystal is for non VC. Maybe the save you were using weren't called sav.dat? I'm not sure how Encounter Database interacts with VC/non-VC save identification. There's only 2 legal shiny Mew that can be transferred up at the moment: 1. Shiny Mew from Japanese Emerald (caught via Old Sea Map at Faraway Island) 2. Shiny Mew from Pokemon GO Master Research.

There's no Shiny Mew that can be transferred from VC Gen 1/2.

They’ve literally told you. Only replace that file, only have it named as ‘main’ (no extensions. for the record, are you transferring the file using FTP?

Wait, we’re you trying to edit the save while the game was running?

You're playing on Citra aren't you. Try playing it on a N3DS or something. But yeah, the game has regular slowdowns, and it is especially noticeable on an emulator. It just sounds like you're trying to associate a regular occurrence (the slowdown) to save editing. Next time, always save and boot up purely in a Pokemon Center. Less things for the game to try to load around you on game bootup. Do it a couple of times, see if the slow down is noticeable on fresh bootup. Only then, perform the save editing, make the same mental note.

It's not. Basically, the mon was illegal to begin with, which PKHeX correctly flagged as illegal. PKHeX then proceeded to fix the illegality (it was a small issue presumably), then proceeds to correctly show you the fixed mon as legal. All working as intended. So, if you want to see how it was illegal before the fix, hold down control and click on the "!", as Kaphotics described.

Regular save edits, like changing learnable moves, changing possible abilities etc, shouldn't cause game lags. All that is likely the artifact of the mind, or the place you saved in (and then the game is trying to boot up and load that area). For save editing to cause any potential game issue, I imagine you'll have to do some kind of crazy edit, and edited yourself into an area that the game can't load, or edited in stuff that the game struggles to load, while writing a bunch of garbage data into other sectors of the save. Basically it all comes down to putting yourself in a situation where the game struggles to load all the corresponding data.

And also make sure the plugins are in that folder, not just hanging around outside it.

Not doing that at the moment. Make sure you unblock the plugins prior to using them.