Hmm, not sure, but I think it probably is from the hall of origin. I've never played Gen 4 however, so I don't know much about the gameplay there.
Wait, if I set my pokemon to private, its legality will never show up, even if the option to display legality for non-public pokemon is selected? How does that work? Does it mean that both public and private must be unticked? (I've unticked that arceus just now, btw, and it's neither public or private at the moment...)
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