VERY COMPLICATED
once you have speaken to professor rowan, your rival and dawn/lucas in the canalave library, go to each of the 3 lakes and battle the comanders there (you will need HM strength and you need to have defeated snowpoint gym leader Candice to get to lake acuity)then once you have done THAT, go to veilstone and speak to the glactic grunt outside the HQ, he will drop an old special key, pick it up and go to the warehouse, use the key, notice it will break when you use it, but don't worry, you will find a new one in the warehouse. then go back out and go to the HQ, make your way through battling several galactic grunts and then defeat the galactic boss. go into the next room and battle commander Jupiter (i think) again. then you can set mesprit, uxie and azelf free. then go to mt coronet from orenbourgh or hearthome, surf across a small section of water and then use rock climb up to the next floor. go northwards through mt coronet battling several galactic grunts, then you have to find your way to the stone pillar bit where the boss is again, he will have awakened dialga/palkia and you have to defeat him + the three commanders. sunnyshore city is now open. (also you get the chance to battle and catch dialga/palkia, so try to do that as well)
beet dialga then go to the hotel (next to pastoria city) and then go to where that guy said the road is closed go past and down to sunyshore
Oreburgh city, Canalave city, Eterna city, Snowpoint city, Hearthome city, Pastoria city, Veilstone city, Sunyshore city
To get to sunyshore, you have to get the snowpoint city gym badge.
No. The last HM is in Sunyshore. Anyway, you have to beat/catch Dialga/Palkia to get to Sunyshore City.
You go to sunyshore city, which used to be blocked off because of a power-outage.It's along Valor lakefront.
Fish with Super Rod in Canalave City and Sunyshore City
It is sunny in Sunyshore City.
In sunyshore city
you have to get dialga after you could go to sunnyshore city.
Go up to the Lighthouse in Sunyshore City. You should see him there. Talk to him and then return to the Gym.
In Diamond, you can obtain a Water Stone in the underground in Sunyshore City.
Sunyshore City
It is in Sunyshore City.(West of the hotel place)
Jasmine on the beach in Sunyshore City.
spear pillar on diamond, pearl, and platinum.
Sunyshore city, where the last gym badge will be.
after you beat Cyrusin the distortion world
To unlock Sunyshore City in Pokémon Pearl and Diamond you have to beat Team Galactic. They can be found at Mt. Coronet.