What are all the legendary Pokemon in Pokemon Diamond and Pearl and how are they all obtainable?

Dialga. you have to have diamond and beat Candice(Ice type gym leader)GO thru Galactic Headquarters, beat Cyrus, and get master ball.Then go thru Mt. Coronet.BEAT Cyrus AGAIN and capture it (Or if you have Pearl, get it by trade.)

Second=Palkia. Same thing as dialga, except you capture palkia instead.

Third=Mesprit, Azelf,and Uxie. Go to lakes Verity,Valor,and Acuirity to find them(after Beating Cyrus twice.) Azelf and Uxie will stay and fight, but Mesprit will run away leaving you to find it.

Fourth=Giratina. After getting the national dex, a path opens up in between Veilstone and Lake Valor, called Sendoff Spring. Find the cave entrance, and go into Turnback Cave. Find a certain room, and there's Giratina. It's level 80, so use a dusk ball.

Fifth=Cresselia. After getting the national dex, talk to that sailor dude who sails you to Iron Island, and he'll tell you his son is sick, that the only cure is a Lunar Wing, on Fullmoon Island, and sail you there to get it. When you get there, run into a clearing and there's Cresselia. It goes away, dropping the Lunar Wing. You go back, cure the sailor's son, and go off and search for Cresselia (just like Mesprit)

Sixth=Rotom. After getting the national dex, go to the Old Chatau in Eterna Forest (Make sure it's between 8:00 pm and 4:00 am.) Go into the room with the TV and press A in front of it.Rotom will come out and challenge you.Now this is really hard, because most of your Pokemon are probably above level 50, right? Well Rotom is level 15, which is a big problem (it took me forever, until i finally got it to red and put it to sleep with my Gloom.) Use a dusk ball.

Seventh=Heatran. After getting the national dex, go to Survival Area,go east, then north, and enter Stark Mountain. GO to the top and enter Heatran's chamber.All you'll find, however, is a dude holding the magma stone! Then he exits, and you have to go all the way to Fight Area. Battle your rival, enter the Battle Tower, where he finally gives it to you. Go ALL the way back to Stark Mountain, enter Heatran's chamber, and you will find Heatran. He's level 80, just like Giratina and Cresselia.

Eighth=Regigigas.After getting the national dex, import Regirock, Regice, and Registeel from Pokemon sapphire, ruby, or emerald.Go into Snowpoint Temple at Snowpoint City and make sure you hav Regirock, Regice, and Registeel in your party.Slide and solve the ice puzzles, and walk in front of Regigigas. Press A, and it will awake and challenge you. It's level 80, like Giratina, Cresselia, and Heatran, but harder to catch than any of the three.

Manaphy and Phione=get Manaphy egg from POkemon Ranger, send it to Sinnoh, then import male Ditto, keep at Day Care with Manaphy, and you have a Phione egg.