Pokemon Diamond/Pearl

[Milk Bubble]

Diamond cuz you get Dialga.

Not really. It honestly depends on what kind of style of fighting you like. Do you like being high damage and waiting turns, or do you like being decent damage but not having to wait a turn. Palkia gets Spacial Rend which does 100 attack, has a high crit. ratio, and you don't have to wait a turn to re-use it. Dialga gets Roar of Time which does 150 attack but you have to wait a turn to re-use it. Dialga is also Steel type and it does not have many weaknesses but it's not super effective against a lot. But Palkia is Water type and is super effective against a lot more types that you would normally see in the game.

Also, here is a list of Pokemon that are exclusive to each game: http://www.serebii.net/diamondpearl/exclusives.shtml

I personally like the Diamond Pokemon better, and I like Palkia better. But when I picked out Pearl I had never played Pokemon before so I had no idea about any of this stuff. So good luck on deciding, and if you can't decide, always remember that the great thing about Diamond and Pearl is that you can go to someplace like Gamefaqs and find all kinds of Pokemon to trade using the wi-fi feature in case you decided the game you got didn't have the Pokemon you wanted.