you can't its only in pearl and platinum you could use GTS or migrate your Pokemon from ruby,sapphire or emerald
Shelgon is the evolved form of Bagon, so evolve a Bagon. Bagon doesn't appear in Pokemon Diamond. To get one, you'll need to trade or transfer one.
bagon evolves in level 30
u cant get bagon in diamond... either migrate it from Ruby Saphire and Emerald, or trade with someone who has perl. (In Pearl yu find Bagon east of Celestic).
you can't catch it in diamond, only in pearl
Bagon is not catchable in Diamond. You can get it in Platinum and Pearl by using your PokeRadar at the northern part of Route 210. You can also migrate it from the GBA games.
Go to: www.serebii.net
Of course, throwing Pokéball at it. But if you mean where, you can't get it in Pokémon Diamond.
Bagon is only available in Pokemon pearl. You can however catch a Larvatar instead of a bagon. you can trade one for a Bagon because another pearl player will want one.
In route 210, use pokerader.
you can get a larvitar in diamond and a bagon in pearl. they are both in the route to the right of celestic town.
Bagon is only available in Pokemon Pearl, but you can obtian it in Pokemon diamond by trading someone who has pearl
shelgon is uncatchable in diamond. U have to catch a bagon in pearl and evolve it and trade.