it depends on what Pokemon you like to train or breed the most.but in my personal opinion i would choose shuckle
you find them in the Pokemon league center good luck!
You can find a Pikachu in Pokemon Pearl in the Pokemon Mansion Trophy Garden. It is in the Backyard. I hope this helped. Good luck on finding Pikachu! :)
A Good Rod is available within Roue 209 in Diamond and Pearl.
you do not find dialga in Pokemon pearl
buy it from the bike shop
By fishing. The Pokemon is Lumineon it can be caught with a Good or Super Rod.
Almost anywhere using a good rod
Fishing with the Good Rod at Eterna City.
Route 222
yes exploud is a good Pokemon for pearl i have it on my team
Trade with Pokemon Pearl or Pokemon Platinum
In Pokemon Pearl, you may be able to find a Kirlia on Routes 203 and 204 using your Pokemon Radar. But be aware, they are very rare! So good luck and Happy hunting! :)