Granted. Poof, you become an Arceus, sitting atop your cloudy throne. You watch the world below peacefully for a long time before trying your hand at creating things, which also goes by nicely. Soon, though, your peace is interrupted by some strange men from Castelia city calling themselves GAMEFREAK. You have nothing to fear from them, as you are essentially God, right? Apparently your powers have no effect on them as they capture you and throw you into an odd windowless room you can't escape from, then force you to have millions of babies that they give out to young irresponsible trainers for free, further increasing their own success. Soon, they no longer have any need of you and leave you to be forgotten in your impenetrable dark cell.
Where else would the event Pokemon come from?
I wish to have this wish-grant rewritten in a much "different" way.