They both learn it at level 30, they should have it when you catch them. If you used an Action Replay then get them to level 30, if you didnt and they dont have it, get the TM it's in Mt. Coronet somewhere.
Palkia does not learn Roar of Time, that's Dialga. Palkia has it's own unique move: Spacial Rend.
www.Pokemon.marriland.com. type in palkia scroll down and look at his moves and just to let you know palkia doesnt learn dragon pulse naturally but he can from a TM. and you can get TM dragon pulse at battle tower.
You catch Palkia and Dialga at level 70 at spear pillar i think. Hope this helps you!
level 100
Giratina does not learn Roar of Time. That move is specifically for Dialga and Dialga only. Because it is Dialga's signature move. Just like Palkia's Spacial Rend and Giratina's Shadow Force. They are the only Pokemon that can learn these moves.
Dialga is easier to catch Palkia is a bit tougher to catch but Pokemon level 75 will do the trick.
You got to max dialga's happiness then go to route 10 you need rock climb then go to a house a old lady will be in the house then talk to her she would say " do you want me to teach the ultimate dragon type move " say yes then choose a dragon type like " dialga, palkia, or giratina
level 100 but dialga, palkia, zekrom, reshiram have a chance to beat it
Dialga and Palkia are at the top of Mt. Coronet.You have to have the Lustrous orb and Adamant orb.Also,you have to of beaten the Elite Four,two.They're both at level 70.
You battle and catch it at Lv. 47. As well as Dialga.
Palkia cannot learn Draco Meteor by leveling it up.An old lady near Route 210 can teach draco meteor to dragon type pokemon
level 70 i caught both of them even garitina!