Tune into Jetix every Saturday morning! =]
After defeating all of team galatic you get to battle/capture Diagla or Palkia, the two legendary Pokemon of time and space... If you have diamond, you get to battle/capture Diagla, but if you have Pearl you get to battle/capture Palkia.
In mt. cornet folow the team galatic people until your at spear pillar battle everyone then, battle cyrus. If you have a master ball, battle palkia or dialga and catch it.
at the summit(very top). you will know if you are going the right way as you will have to battle plenty of team galatic to get there.
By defeating them in a Pokemon battle.
Pokemon battle platinum
go to mt cornet and battle dialga or palkia or girtina depends if you have diamond pear or platinum
you can catch palkia in the mount corunet after you beat Cyrus in a battle in his lab and there is specific path for getting in one side of the mount corunet keep looking until you find a place where its snowing in mt coronet.
you will need to go through Mt. Coronet into Spear Pillar and then battle two galatic grunts.Then your guy will move up to see Cyrus create Palkia and then battle Commander Mars and Jupiter with your rival and then battle Cyrus.He uses Honchrow,Weavile,Crobat and Gyarados.Beat him.Battle with PALKIA and cath it.Then you can go to Sunyshore City!
He is thed boss of team galatic. you will have to battle him twice.
If playing Pokemon diamond and pearl go to galatic teamso you could get key then battle the boss and you will get master ball free the legendary Pokemon then go find palkia or diagla in the mt. cornet then you will unlocked the path to sunyshore city
first defeat the elite four and the champion. go to sangdem town and talk to dawn/lucas. he/she will tell you something about dialga and palkia(i.e.time and space) appearing at the spear pillar. then go inside the lab and talk to rowan. then go to the spear pillar and straight at front you will see a blue dimension, talk to it and it will ask you if you want to battle it. this blue dimension is dialga. after you battle it another pink dimension at right will appear that is palkia. if the pink dimension does not appear then go back to the entrance of spear pillar. go out and again come in then probably the pink dimension will appear.
No you can not battle dawn in platinum:( but you do work with her several times against team galatic