there are no other regions.
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.
You can't. Not without and not with the national dex, ou can't get to other regions at all in Pokemon Diamond and Pearl
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 are no other regions accessible* other than the starting Sinnoh region. *Excluding other games.
The entirety of Pokemon Pearl and Diamond is set in the Sinnoh region. There is no way to revisit any of the other Pokemon world regions.
No, there are no other regions in Pokemon Diamond.
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.
you cant
Trade with another Pearl or Diamond.
No.
Dont think so
doesn't matter, the only difference is the rare Pokemon (palkia for pearl and dialga for diamond) and you can only get stunky on diamond not pearl and you can only get Scorpio on pearl not diamond. Other than that they are both the same and both as good. hope i helped!