Are there any Pokemon that roam Sinnoh in Pokemon Pearl?

Question

I'm curious

Answer 1

Yes, there are a two legendary Pokemon that roam Sinnoh in Diamond/Pearl.
After going to Lake Verity, Mesprit will start to roam Sinnoh.
After you defeat Team Galactic at Mt. Coronet and you cure Eldritch's son's nightmares, Cresellia will start to roam Sinnoh.

Source

Comments

Wait, what Pokemon for the second one?

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Whoops, guess I forgot to add that last part before I submitted the answer.