All you need to change is Dialga for palkia.
I remember finding one south of Vielstone city, but Diamond had it south of Stark Mountain... Perhaps this is because Ryhperior is in the new Sinnoh dex.
A good team would probably be the following: Ryhperior (for attack) Steelix (for defense) Houndoom (for special attack) Milotic (special defence) Aerodactyl (for speed) Altaria (all round contribution)
Here is a list of all legendarys on Pokemon Diamond or Pearl and additionaly how to catch them. Dialga is only available on Diamond and can be caught at the Spear Pillar, Palkia is only available on Pearl and can also be caught at the Spear Pillar, Mesprit can be first seen at Lake Verity Carvern and then can be caught roaming Sinnoh, Uxie can be caught at Lake Acuity Cavern, Azelf can be caught at Lake Valor Cavern, Cresselia can be first seen at Fullmoon Island and then can be caught roaming Sinnoh, Regigigas can be caught at Snowpoint City Temple by having the three Regis in your party its statue will come to life, Heatran can be caught at Stark Mountain, Manaphy can be caught by migrating its egg from Pokemon Ranger, Phione can be caught by breeding Manaphy with Ditto or another Manaphy, Shaymin can be caught by obtaining Oak's letter and doing Flower Paradise on Route 224 (next to Victory Road), Darkrai can be caught by obtaining the Members Pass going to Canalave City and entering the fomerly shut door and going to Newmoon Island, Arceus can be caught by obtaining the Azure Flute (Heavens Pipe), going to the Spear Pillar and playing the flute accesing the Hall of Origin u forgot about spiritomb u can catch him by talking to people underground 32 times but that does not include the minnors you can also get ryhperior by trading rhidon holding the protector that you find in the desert (trad it to a freind so you ca have it back) and it will evolve into ryhperior and there also rotom that can only be caught at night between 8pm and 4am at the old chateau in the eterna forest by clicking on the tv in the up staire room and thumping the tv and rotom will pop out and battle you.(make sure you have a low lvl Pokemon like lvl 18 because rotom will be lvl 15 so you don't want to kill him) lolola999