How do I get the National Dex in Pokemon Diamond Version?
I don’t know why so much people think that there are 150 Pokemon in the Sinnoh Dex on D/P. There are 151 Pokemon in the Sinnoh Dex. You probably didn’t see either Manaphy or Palkia. To see Manaphy go to the Mr. Backlot’s Mansion (I think it’s at rt. 212). Go to Mr. Backlot’s room and talk to the book, you’ll see a picture of Manaphy which will be recorded in your Pokedex. To find Palkia you need to go to Celestic Town and go to the elder’s house (Cynthia’s grandma), then read the book and you’ll see a picture of Palkia which will be recorded in your Pokedex. Then go and talk to Prof. Rowan in his lab in Sandgem and Prof. Oak will come and upgrade your Pokedex to National mode.