The Sinnoh region is the only region in Pokemon Diamond, although the area in the northeast of Sinnoh is like a mini-region.
No, there are no other regions in Pokemon Diamond.
No.
Unfortunantly you cant go to other regions in Pokemon diamond and pearl. its not like leafgreen,firered,gold,silver and crystal version where you travel to different regions. You can't, Sinnoh is the only region available in the game.
There is only one region in Pokemon diamond.
there is only the sinnon region is Pokemon diamond
No you cannot go to other regions in Pokemon Pearl or Diamond version but in Pokemon Heart Gold and Soul Silver you can go to the Jotoh region.
There is none
What you have to do is catch all the Pokemon from all the other regions(complete national dex.
Pokemon Diamond and Pearl starts in the Sinnoh region and doesn't allow the player to move to other regions. It is considered the fourth generation of Pokemon.
there is no way to
there are no other regions.
Yes you can. Mainly once you beat the elite four, but other more common Pokemon can be found that are not exclusive to the Sinnoh region.