You have to see them
You can't catch Charmander in Pokemon Diamond. You have to import it from Leaf Green or Fire Red.
You would have to complete the Pokedex, and then talk to a guy in the Game Freak building.
gotta catch it first
You have to catch at least 60 Pokemon and you have to beat the elite four including your rival
In Pokemon diamon, diglett has arena trap. You can catch a Diglett at the top of route 228. (you can only get there after beating the Pokemon league and talking to the sailor at snowpoint city).The only other way to get this Pokemon is to complete the sinnoh pokedex than go to proffeser rowan for the national pokedex, and than trade one from leaf green or fire red versions. (you have to get the national pokedex before trading one from another version).!!!Good Luck!!!
you can catch them on Pokemon pearl, diamond, platinum, and one or two are found in Pokemon rangers and can be transferred to your Pokemon pearl/diamond games. Also Pokemon can be transferred from and of your Pokemon DS games, such as Pokemon leaf green. To transfer your Pokemon from a gameboy game you have to go to the palpark which you get after you complete the sinnoh pokedex.
migrate from these Pokemon games ruby sapphire emerald fire red and leaf green requiers national pokedex (only migrates 6 Pokemon a day)
put leaf green in SLOT 2 and Pokemon diamond in SLOT 1 and catch a Magby in route 227 (you must have a national pokedex to catch one and the wild magby may not have it!)Joe7596
If you have 100 Pokemon in your Pokedex (Caught of course), then you complete the other 4 islands available in the game complete with a Team Rocket base.
Poliwrath
To catch every Pokemon, you need action replay for the few last diamond legendaries. You will need Pokemon fire red/leaf green and emerald. Migrate them to Pokemon diamond. In Pokemon diamond, fill up your pokedex by catching Pokemon normally or with poke radar, or use gts. It will take a long time to catch all Pokemon
In Pokemon Leaf Green, you can catch Pokemon in the grass, water, or in a cave.