you can't. You might find one in the battle frontier, but it won't register in your pokedex...
In "Diamond," you can find a trainer in the Victory Road that will have a Whiscash.
A Pokemon guide that you can find in the forest.
you need a cheat that can catch a trainer's Pokemon to have lapras. because there is a trainer that has a lapras.
in Pokemon diamond go to iron island and find a camper trainer and fight her
the trainer is on the way to route 224.
In Pokemon Diamond/Pearl, you find a old man at route 212 with a Leafeon.
you battle a Trainer and the trainer will say before you fight him EVERYONE
Elite Four Aaron has one.
cherrim you can find it by battling a certain Pokemon trainer on iron island
You can't catch Charizard in Diamond. You'll have to migrate or trade Charizard to get it in Diamond. You can have a Charizard in FireRed/LeafGreen and HeartGold/SoulSilver and X/Y, if you evolve Charmeleon. To get Charmeleon, you need to evolve Charmander or in X/Y you can find it at the Friend Safari. In FireRed/LeafGreen Charmander is a Starter from prof. Oak and in HeartGold/SoulSilver you can get it as reward from prof. Oak for defeating Red.
No trainer has a combee in diamond and pearl but you can find a combee on trees you put honey on. There is a trainer in route 208, she has combee and Roselia
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