We don't know the full formula for Hadou Regis. We also don't know the trash data. Therefore recreation is not a good idea.
As for Pokecheck, I have all of the not-obviously-hacked private uploads. It's not possible to determine a formula since I don't know which (if any) are legit.
As for known legits, I know of 2 Pokemon in 3rd gen format and they are with private collectors.
Most likely other events had flags too. I think I remember Bulbapedia saying something about 48 celebi total being able to be transferred? How is that determined?
The only thing PKHex doesn't handle is trash data. It doesn't matter though cause as soon as you move to gen 6+/bank, the Pokemon trash data is then determined by the app that retrieves the Pokemon from bank.
So for practical purposes PKHex is exact.
GBA carts specifically require Rudolph's GBA Backup tool. It is kind of painful to use and not 100% fool proof, sometimes it fails.
Delta Blast Burn is right, for NDS carts, you can just use CFW/Checkpoint.
It looks like there is still 10hrs until distribution, and according to pokemon.com you get 1 of each berry. The idea being that you should plant them.
@Jeong, do you have these pokemon? You can attach the PK5 files in a private message to me. Also please private message me any information you have and we can post it for you!
Thank you for helping.
Someone should make sure we have all seeds for English then I can generate the remaining Japanese. Quicker then trial/error redemption on Japanese disc.