you need to cacth dialga first
use ground type
In sunyshore city
from that gym leader on the beach of sunyshore city (must have beaten the 8th gym)
It is sunny in Sunyshore City.
Gym Leader Jasmine of Johto will give it to you. She is located at the shore in the northeast part of Sunyshore City.
you have to get dialga after you could go to sunnyshore city.
in sunyshore city
Very north of sunyshore city.
Sunyshore City
Jasmine on the beach in Sunyshore City.
the gym leader volkner uses electric Pokemon
you must talk to him in the lighthouse, in sunyshore then you can go in