How do you get the national Pokedex in Diamond?

Question

I need it to get an eevee!

Answer 1

You have to beat the Elite 4 and complete the Sinnoh Pokedex consisting of 150 Pokemon.
This will also allow you to go to the Survival Area.

Comments

do you have to catch them all or just see them all

Answer 2

you get an eevee from Bebe. Her house is next to the Pokémon Center in Hearthome