Your Pokemon X/Y Thoughts (SPOILERS ALERT)

[Ghost Nappa]

Dark magic and/or human sacrifice.

Use an action replay on a DS or gameboy era game to get to the events and transfer up.

But it won't be legit and have a large amount of "questionable" information attached to it.

What, like RNG shinies? Honestly, if you can't get it normally, you might as well. Fake over not at all.

RNGs are legit Pokemon though and recognised even to Game Freak/Tournament Organisers. RNG Abusing isn't even on the same level as blatant cheating. With Action Replay devices, you'll have weird information such as
Jirachi: Found level 22 on Route 204

Compared to an RNG'd Pokemon
Pikachu: Found level 22 on Route 204

Obviously hacking is the players choice, it's just going to have that weird information about being obtained in some random area. Besides, you can always RNG Mystery Event Pokemon too.
OR, if that is still too much effort, just download legit Pokemon from here that have been RNG abused or not
Pokecheck Keldeo example

There are no Pikachus on route 204.