Go to Spear Pillar, beat Team Galactic and capture Dialga/Palkia. Then the road to Sunnyshore is open.
You can get one in sunnyshore city or underGround
there will be a man fishing in sunnyshore city
After you defeat Volkner in Sunnyshore City, a girl on the beach will gift it to you.
sunnyshore city
sunnyshore city is were you find it
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
Sunnyshore City
at sunnyshore city
sunnyshore city if you have palkia
In Sunnyshore city same as pearl/diamond.
Lumineon and you add to pokedex by fighting a swimmer out side sunnyshore city!