Blank Transparent Square

Which came first, Necrozma or Arceus' egg?

Dinosaurs.
(joke)

Lol

Its pretty stupid confsidering there is no evidence pointing towards it and it came from another dimension

But where did Arceus's egg come from?

Well lets say they did, this just devolves into a whole nother argument about where necrozma comes from, some things are just better left unanswered

Who knows at this point

So there is no point about wondering where arceus egg came from because no one knows and there isnt anything to tell us, maybe it just formed out of no where, maybe something unknown createdit

ok?

But arceus came before necrozma

We don't know that.
Ultra Space could have existed before the Pokemon universe.
But at this point, people are theorizing that Arceus is also an Ultra Beast.