Piggy-backing on this, we can’t tell you where to find the files 00040000001A8900 and 00040000000EC500 in the Gigaleak, but if you ever manage to buy a second hand 3DS (maybe Pokémon Center?) with those files[apps/games], you can use these saves for custom cards that can be received via vanilla device (has to be locally, can’t be done over internet)
But as said above, the sender needs to be a hacked (for modifying the save).
Anyhow I’m locking this thread, since main question has been addressed.