You have to get the HM rockclimb and climb to the top of Mt. Coronet and catch Palkia. Then the man will be gone. VERY IMPORTANT!!!! DO NOT WASTE YOU MASTER BALL ON PALKIA!!!! There will be a Pokemon later called Cresselia who travels around like Mesprit will do but is even harder to catch then Mesprit. Hope this helps!
You can dig for it undergrond or you must get it in sunnyshore. if you passed it up, you must dig with the explorer kit.
cach pearl the legndary Pokemon
After you defeat Volkner in Sunnyshore City, a girl on the beach will gift it to you.
You can get one in sunnyshore city or underGround
there will be a man fishing in sunnyshore city
Go east of Valor Lakefront down the stairs.
sunnyshore city
sunnyshore city is were you find it
You have to go to Sunnyshore City and battle the Blonde haired guy if you haven't got passed the guy you to capture Palkia/Dialga then he says the power is back on
Go to Spear Pillar, beat Team Galactic and capture Dialga/Palkia. Then the road to Sunnyshore is open.
as your going to sunnyshore city its in the grass north of the beach
In sunnyshore city in front of the lighthouse there is one on the ground