General
Is PKHeX available for the Macintosh OS or Linux?
No. You can use virtualization software like Parallels or VMWare to run a Windows OS virtual machine.
My Pokémon won't work on WiFi battles or can't be traded. Why?
This is usually a Pokémon legality issue. These problems aren't dealt with in the PKHeX subforum; see the announcement regarding cheating online.
What is the Mystery Gift "Received List"?
Every Gift has a unique ID associated with it. When you receive a Mystery Gift the game flags your save file as having obtained the gift, and doesn't allow it to be obtained again. PKHeX will set the used IDs for you; an ID can be deleted by right clicking the ID and choosing to "Delete".
Can PKHeX create backups automatically?
Yes, create a "bak" folder in the same location as the executable, and PKHeX will export a backup of every new save you load.
Generations 7, 6
Is PKHeX compatible with Powersaves or Sky3DS?
No. It never will be. Save files must be decrypted in order to load & save, and must be resigned before put back into your cart data.
Generations 5, 4, 3
I'm using a flash card (R4, Acekard, etc) or emulator and my save file isn't able to be loaded. What's going wrong?
Make sure the save data is in 4 megabit format (512KB) for Gen4/5 games, and 128KB flash for Gen3 games.
Generations 2, 1
Does PKHeX support these games?
Yes! Be sure you are exporting your save file in the "Battery" format (raw save file, not emulator specific).