When you defeated the Elite Four and the left is N, go all to the top of N's Castle when you do, the Light Stone would brighten up and Reshiram would appear. After you catch Reshiram, N would battle you.
There is a fanmade Pokemon Cursed Black version on cartrige, however there is a rom you can download (i can not find the website again, I will improve the answer when i do find it, sorry)
Does chaos black version even exist? Yes
You can't, you can only find that on the white version. You can find Tornadous in Black.
Braviary is only in Pokemon White. Pokemon Black gets stupid Mandibuzz -_-
Vullaby is a version specific pokemon, specific to Pokemon Black. You will need to get someone to trade it to you.
big kmart
Trade it with people who have Pokemon White version as you cannot find wild Rufflet in Black
You can find it at Walmart, Target, and Game Stop.
you cant get zekrom in black but you only trade to get it
You cannot find Vullaby in Pokemon White Version. It is exclusive to Pokemon Black as Rufflet is to Pokemon White.
you find it in the giant chasm
Lighten up, nerd!