Palkia, your starter (I chose empoleon), steelix, azelf, plus two of your choice. Make sure the level of your starter and palkia are at a minimum of 60, then it's quite easy.
you have to defeat the elite four and then the champion
beat the elite 4 then champion Cynthia
beat the elite four and become champion
You can get it from Bebe (the house beside the Pokemon Center in Hearthome City) after you defeat the Elite Four and the Champion.
u cant without an action replay
To defeat Team Galactic, complete your pokedex, and defeat the Elite Four and Champion.
Cynthia is the Champion so you will see her when you beat the Elite Four
Cynthia is the elite four champion. She has also got very rare Pokemon you have never seen!!!
The champion is Pokemon Diamond, Pearl and Platinum, is Cynthia. She has various Pokemon-types. She is the Sinnoh Champion. Her Pokemon are Spiritomb, Lucario, Togekiss, Milotic, Garchomp and Roserade. In Platinum, Cynthia has a Togekiss. In Diamond and Pearl, she has a Gastrodon.
Cynthia IS the Sinnoh region champion, so to face her you will need to collect all the badges and defeat the Elite Four.
In the elite 4 league. Beat all 4 and when u r at the champion f00k her off
You fight the Champion. Of course he is really hard... Then you go to Spear Pillar. At Spear Pillar you can catch Palkia.