I'm assuming you mean Groudon. There are 3 ways to get it in diamond, unfortunately none are in-game.
1. Migrate it from a previous game.
2. Get it off WiFi.
3. Cheat/hack.
when you get your national dex, an area that used to be full of trees on route 214 will open a space called the spring path. enter inside and have a team full of levels 50-75. keep following the maze then you will enter tall grass. find the opening to a cave. go inside. keep running inside and i prefer u be prepared with aton of ultra balls and max repels.there are alot of wild pokemon in that cave. anyways keep going forward untill you see a visible pokemon. that would be giratina. good luck.
(I think) after you get 8 gym badges Spring Path opens up in some part of the region, and you find him in a cave.
you can't find garintina in Pokemon white you can only find unova region legendary's and not all of them
At turn back cave
You can not find or get manaphy on Pokemon diamond but you can by hacking, trading or... if you have Pokemon ranger you have to complete the manaphy mission and then you can put it onto diamond.
You can't find a Ho-ho in Pokemon Diamond. You have to migrate.
you can find legendary Pokemon by using your Pokemon tracker
no such thing as fania on diamond
You don't. Red's not in Diamond.
You can find Pidey in a Pokemon Outbreak in Pokemon Diamond
where do i find a totodile in Pokemon diamond/pearl on nintendods
You can not find or get manaphy on Pokemon diamond but you can by hacking, trading or... if you have Pokemon ranger you have to complete the manaphy mission and then you can put it onto diamond.
You can't find a Ho-ho in Pokemon Diamond. You have to migrate.
To get a Manaphy in Pokemon Diamond you have to get Pokemon ranger and defeat it and you have to trade it to Pokemon Diamond,Platinum or Pearl.
its not a Pokemon
Not really that rare... in Pokemon Diamond you can find Sunkerns on Route 204
you have to catch all of the pokemon in diamond or SEE all of the pokemon
you can find legendary Pokemon by using your Pokemon tracker
there isn't a Pokemon ranch on Pokemon diamond, its a complete other game! there isn't a Pokemon ranch on Pokemon diamond, its a complete other game!
You can't find Steven Stone in Diamond
you can't find metang in Pokemon diamond you have to get beldum in swarm when you get the national pokedex and then evolve it