when u finish the sinnoh dex you go to prof. rowan and talk to him then prof oak (from past games) will run in and talk to u than u will get the national dex
The credits roll after you beat the Elite Four. However, I would classify the game as being completed after you have seen all of the pokemon in the Sinnoh Pokedex and the National Pokedex.
You get the sinnoh one basically after starting the game, the you get the national pokedex when you´ve completed the sinnoh pokedex (by seeing all the Pokemon in sinnoh)
well you need to have all your Pokemon in your pokedex and when you get your national pokedex you will get breed
you have to catch all of the pokemon in diamond or SEE all of the pokemon
get all the legendarys
You can get the National Pokedex in Diamond when you see all 150 Pokemon, but not necessarily capture them.
Nothing.
If you used an action replay card, I'm guessing it's a glitch. ACTION REPLAY CARDS RUIN YOUR DS! no they don't the pokedex cheat doesnt give you all the Pokemon in the game it just completes ur pokedex
you just keep catching all the Pokemon
Catch all the Pokemon.
the Pokemon in diamond are sinnoh Pokemon i suggest http://Pokemon.marriland.com/diamond_pearl/pokedex to see all of them
Sadly no, but there is one to get all the Pokemon in your pokedex.