you can get him by cheats but without the mystery gift i am not sure i will try to ask gamefreek for an update.
Not without cheating
you have to get the arceus event on mystery gift.
You can't.
As of now, there is no way of catching Arceus without cheating or hacking.
You can't
You can either get the mystery gift arceus, the mystery gift azure flute, and lastly action replay.
Pokemart or Mystery Gift
No, you cannot get Arceus with or without completing the game. The only way to get Arceus is by a Nintendo Event involving Mystery gift and the Azure Flute.
the only way you can get arceus without cheating is by getting a mystery gift, you get them via wireless internet, look up when the arceus event is coming
how can i catch arceus
june 30th
you can't unless you have action replay and go to grass