if you have seen all the Pokemon in the sinnoh dex, talk to professor rowan and then oak will come in and upgrade your pokedex to the national dex. Then you go to snowpoint city. see there is a man with a boat on the southern side? talk to him and he will take you to the fight area.
professor oak gives you the national dex in rowans lab. after you finish the pokemon legue you talk to professor rowan then oak comes to you and gives you a national dex but only if you finish the first pokedex. if you haven't finished the first dex you need to go and finish it. then go back to professor rowans lab and oak will be stood outside or inside and he will hand you the national dex.
Go to professor Rowan's place in Sandgem town and talk to him. Then Professor Oak comes and gives you the national pokedex.
If you mean on your DS then it is to talk to people otherwise I do not know sorry!
go out of hearthome and there is a fishemen talk to him and hay pest o you have a good rod
You can find Dawn at Professor Rowan's research lab in the Sinnoh region.
professor Rowen
After you defeat the Elite Four go to sandgem city and talk to professor rowan and then professor oak will come they will talk then give you the nationaldex
finish the national pokedex and talk to professor rowan
you have to see 150 Pokemon then talk to professor oak..
Complete your Sinnoh Pokedex and talk to Professor Rowan. You get the National Dex and a Poke Radar.
After you finish the game platinum pearl diamond you will go to the town where the Pokemon lab and talk to the professor.
u get national dex
See all 150 Pokemon in the Sinnoh Dex and talk to Professor Rowan.
Professor Elm is not in Diamond, he is in Gold, Silver, and Crystal.
you complete the national pokedex and then talk to professor oak and he will give you it hope i helped
You talk to the manager of the pokemarts and he will tell you a code. Then you tell the professor the code.
You must see/catch all the Pokemon in the Sinnoh dex and then talk to Professor Rowan.