What is national pokedex?

Question

I want to know if there is a way to obtain the national pokedex in pokemon-sapphire.and may I can migrate my pokemon from sapphire to diamond without completing the diamond version but after completing only pokemon sapphire

Answer 1

You can get the National Dex is Sapphirre, and fairly easily. All you need to do is trade with FireRed/LeafGreen, and you will automatically get it. As for your migration question, you can not migrate until you get the National Dex in Pokemon Diamond.

Answer 2

National pokedex is the whole list of pokemon from all region! You will get national pokedex after you see all pokemon in region pokedex (like Hoenn Pokedex and Sinnoh Pokedex). If you have national pokedex, up to 493 pokemon can be transfered into national pokedex!
and your second question, no! you can't migrate it... you can migrate only if you already obtain national pokedex in Diamond...