a cirtificate saying you completed the game
No
I don't know if there is a code. But you can complete de Dex by seeing all Pokemon in platinum. All Sinnoh-dex Pokemon can be found ingame.?
You can't get the dex by doing nothing you have to beat the elite four with over 60 Pokemon species in your dex.
There is none. There's only the Hoenn dex. no that guy is wrong. first you need to have caught about 60 Pokemon and you need to have traded with another person then go show prof birtch in the first town and he should give you the national dex. if he doesn't then you need to get more Pokemon. No that guy is wrong you have to get all the Pokemon then you get a Pokemon from a different game then you go to prof oak but if he doesn't give it to you then get more Pokemon from a different that's how i did it.
There are 210 in the Sinnoh Dex, 493 in the National Dex {including EVENT Pokemon}
The last Pokemon on the national dex is Arceus.
Piplup's National Dex number is 393.
omg ditto is only in the national dex noob :) omg ditto is only in the national dex noob :)
In Pokemon Platinum to get the National Dex you will need to have seen all 210 Pokemon in the Sinnoh Dex then talk to Professor Rowan and then after a while Professor Oak will give you the National Dex!
talk to oak in eterna city and he will give you the national dex
Capture all the Pokemon On the National Dex.
You get the National Dex as soon as you start the online game.