How do tu get Diagla and Palkia on Pokemon Platinum DS?

Two ways. The first one is simple, trade them off of DP. The segundo is the basic but harder option. Beat the Sinnoh League, talk to someone in Celestic Town, obtain the Lustrous and Adamant orbs in Mt. Coronet, go to Spear Pillar to obtain these legendary pokemon.

tu go to mt conet in a cave in mt cornet there is 2 pokeballs and a rock kia's and collect the pokeballs in them are the 2 orbs (palkia's and diagla's) go the to rock and hit the A button and get the lunar wing go to spear pillar and there will be 2 portals rosado, rosa & blue rosado, rosa is palkia's & blue is diagla's after facing 1 of them go into the cave and go back out and go into the other portal. Be carful they're level 70.

hint)if tu dont read the whole message tu will fail i now its long but just do it)get both orbs abdamant orb and the listroes oeb(both in a fog room on mt.coronet hearthrome side)make sure tu have gotten 8th badge and hm waterfall then go to were tu fought/capture girintina on the sides will be one rosado, rosa portal and one blue portal go in whichever tu want first but if tu want the other one tu will have to exit and renter mt coranet o yea before tu take the orbs to go get dialga and palkia tu will go have to talk to the elite fours champion grandmother in celistic town with the orbs in your invetory she will tell tu about the story that happened in alomos town because tu werent born yet and after lisenign to her yap on and on then go to mt coranet

tu get Dialga and Palkia at the Spear Pillar. And tu get dialga and palkia por defeting first Saturn and Mars then tu defiting Cyrus and then youl find Dialga and Palkia and then a portal to the Distortion World then a shadow would apear the shadow of Giratina.You would not be to capture Dialga and Palkia because tu would be in the Distortion World,but youl be able to capture Dialga and Palkia wen tu defet Cinthia.Then tu go to the Spear Pillar and then yould find two vortex blue for Dialga and rosado, rosa for Palkia then tu go and press the boton A,then tu can figth Dialga and Palkia and see if tu capture dialga and palkia.

tu know how at the Spear Pillar Dialga and Palkia disappear? Well, after tu are into the Hall of Fame, go to Celestic town and talk to the elder lady inside the big building. She'll tell tu about Dialga and Palkia, then go to the Spear Pillar, and tu will see 2 crystals. Those are Dialga and Palkia. Press A to battle Dialga, then go back in Mt. Coronet, and go back to the Spear Pillar, and battle Palkia.

There are four ways.
1st: tu get someone to trade with tu from the Global Trading Center (or whatever it is called)but that's very hard to do.

2nd: Trade them from your Diamond and Pearl games.
You'll need two DS systems though.

3rd: Buy an AR if tu don't already have one and hack...

4th and final way: The simplest way is to beat the elite four and go back to Spear Pillar to catch them. I'm not sure if tu have to complete the Sinnoh Dex though first though.

tu need rock climb and tu need surf and rock smash and tu have to go to mount cornet then tu see garintina then tu have to battle diaga and palkia

Bataling with a realy strong pokemon like mew