pkmn-chest VS nds-constraint

In my experience, the best way to cheat in Pokemon is using save editors rather than codes. For hacked 3DS, PKSM is the way to go. For hacked DSi, Pokemon Chest. Both are about the same thing: a combination of Pokemon Bank without needing to connect to the internet, moving pokes between generations, and a savegame editor that can create and edit Pokemon as well as some other stuff in your save. PKSM is the better app since it supports generations 1-7 on 3DS, but Chest runs on a DSi and handles generations 3-5.

There aren't any official video guides, but there is a wiki on its GitHub: https://github.com/Universal-Team/pkmn-chest/wiki

Unfortunately, no. You can however use pkmn-chest to transfer the Pokémon between the games.

On 3DS there's PKSM and on DSi there's pkmn-chest which can edit the Pokémon games right on console or you can also easily dump your saves, edit with PKHeX on PC, and inject using homebrew as well.

Huh weird... Are you loading it from your flashcard kernel? If so try loading it from HBMenu/TWiLight/GM9i as explained on the wiki.

Try using the latest release instead of a nightly: https://github.com/Universal-Team/pkmn-chest/releases

You may also be able to just use PKSM, pkmn-chest, or PKHeX to edit the save if you have access to it.

I don't generally recommend video guides, but there is a text guide on its wiki.

You could use pkmn-chest to move it, when going from an older generation to a newer generation the transfers are done exactly the same as the official method so the Pokémon will stay legit and all.

You know it's been a few years since we didn't need to use patches anymore thanks to nds-constrain, right?