Trade them with friends, but otherwise, the ones you can only get in pearl, like palkia, you can't see them. Unless you cheat, wich i wouldn't recommend.
Exclusive to Pearl
you get it when you see every single Pokemon in Diamond or Pearl, then go and speak to proffeser rownan
if you want Entei in Pokemon Diamond/Pearl you'll need a Pokemon FireRed/ LeafGreen that you started out with Bulbasaur. In FireRed/ LeafGreen if you started out with Bulbasaur [Grass-Poison] after you defeated the Pokemon and if you run into Entei in the wild capture it and migrate it into to Pokemon Diamond/Pearl through Pal Park. If you want to migrate in Diamond/Pearl you'll need to see all 150 Pokemon yes both Dialga and Palkia. You'll see Dialga in Pearl from an elderly woman who's shows you its picture and the same with Palkia in Diamond from the same elderly woman in Celestic Town. This adds its data to your Pokedex and less Pokemon to see in Diamond/Pearl.
Pokemon Diamond, Pearl and Platinium does not have any desert areas.
for diamond and pearl there are 150 Pokemon u need to see . in plat nium u neeed to see 210 Pokemon.
there are 150 kinds of Pokemon that you can see and/or obtain. Unless you have friend trade you Pokemon that you can only get in pearl to you, you'll never obtain them all. In Pokemon diamond and pearl all you have to do is see the Pokemon and you get its data unlike the older versions where you have to obtain them.
In Pokemon Diamond, Pearl, and Platinum you can find Buneary in the Enterna forest.
trade diamond from Pokemon diamond onto Pokemon pearl
You trade Magmar from Pokemon pearl,diamond,or platinum to ether Pokemon pearl,diamond,or platinum.
You cannot see Murkrow in Pokemon Pearl. You must get one from the GTS, trade with someone with Pokemon Diamond, or migrate it from a GBA game.
When you see Giratina there you go through a portal and you have different clothes thx guys
THE POKEMON THAT ARE NOT FOUND IN DIAMOND AND PEARL ARE:MANAPHY PHIONE