back in '07 I choose Pearl bc i though Palkia was cooler. I feel bad that I dont use him that much anymore. However, D/P is the only pokemon game where the legendaries are not evenly matched (even when one legend had a type advantage, it then had a move/ability/stat boost that made it even, like Groudon's one turn solarbeam and sure-hit Thunder (if kyogre's drizzle is in play) to balace its weakness to Kyogre's water moves.
But palkia is at a disadvantage because its dragon moves do neutral damage to Dialga but Dialga is super effective and is often faster. The fact that Roar of Time has a one turn rest afterwards does nothing to give our Palkia the advantage. Poor Palkia, his only option is Earthquake, but its no match to Dialga's defense and earthquake's lack of STAB.