all except unow and all legendaries
catch all 150 original Pokemon i believe if not its you have to catch all of them from the hoen region too
yes you have to defeat all the champions before catching a legendary pokemon
you can't catch more pokemon. you have to get rid of some pokemon.
You can't catch one at all. You'd have to trade one from FireRed/LeafGreen.
ALL POKEMON except legendaries and pre evolved forms.
all except unow and all legendaries
You can breed all Pokemon except: Legendaries, Babies and Eggs.
All except baby Pokemon and legendaries the exception being manaphy.
Catch all the Pokemon!
go to this page http://www.serebii.net/diamondpearl/legendaries.shtml this page has all the legendaries you can normally catch in in Pokemon diamond/pearl all other legendaries you have to transfer from a 3rd generation game
You have to trade and catch as much Pokemon as you can
g;r;g;g
catch all 150 original Pokemon i believe if not its you have to catch all of them from the hoen region too
I put a link to guide on all the legendary pokemon in Pokemon Black in the related links.
You could try to catch other legendaries, breed Pokemon, look for Pokemon you want in the GTS...There isn't much to do after you've caught all the legendaries and beaten the game, though, so be careful not to catch them all in one day.
catch all the legendaries. when u done that catch all the Pokemon in national dex. when u done that...... get platinum.