go to route 20
You can find whismur at route 503, and mankey is currently a swarm pokemon, so you'll have to wait or trade for it.
Breed a Loudred and hatch the Egg
You can't find a Whismer walking around.
go to Sandgem town and talk to the girl that says which Pokemon is where
whishmur can be found in: Kanto: Route 4, 6, 9, 10, 13, 21, 22, 24, 25, 26, 27, 28 Johto: Mt. Silver, Route 30, 31, 32, 34, 35, 43, 44, 45, 47 and the Ruins of Alph
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