Yes, but there is a simple way, once you have found all but palkia in the Sinnoh dex, go to Celestic Town and speak with Cynthia's Grandmother. She will read you a book that contains a picture of Palkia, which is all you need for your entry into the Sinnoh Dex. Hope this helps :D
No is doesn't only if you complete the national dex
What you have to do is catch all the Pokemon from all the other regions(complete national dex.
The volcano in Pokemon Diamond is called Stark Mountain. Stark Mountain is located at the end of route 227. This is were players can capture the legendary Heatran after unlocking the national Pokedex.
Complete National Dex, it takes forever
oak will thank you on the PC that is it what a blow out
There are none but there ARE the National Dex Complete and Shiny and Regular Pokemon Modifier. NOTE: SHINY AND NATIONAL COMPLETE CODES ARE EXTREMELY LONG!!!
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!
No, there is not a Pokedex after the National Pokedex in Pokemon Diamond Version.
complete a normal pokedex then go to palpark and talk to prof oak
Just train your Pokemon till they are all level 100 then battle your friends.
Complete your Sinnoh Pokedex and talk to Professor Rowan. You get the National Dex and a Poke Radar.
you have to complete the sinnoh pokedex and get the national pokedex hope i helped :P