You find Coballion in a cave east of Chargestone Cave, get there by Surfing, inside look for an old man, speak to him and look in the cave for Coballion.
Once you find Coballion, you can find Virizion in Pinwheel Forest(Surf and Cut to it), and Terrakion in Victory Road.
In Black/White you no matter what get Reshiram/Zekrom.
If you import a special-event Shiny Raikou/Entei/Suicune or Celebei... you can find Zoroark in Lostlorn Forest and bring your special-event Shiny Raikou/Entei/Suicune to the trailer. If you bring the Celebei to an empty building with a woman and a boy together, the boy is Zorua.
To find a Wild Volcarona, go to the Desert Castle where you met Ghetis there looking for the White/Black stone, take a right and go up from there an find a hole. Navigate through their for a LV 70 Volcarona.
And you get a Victini by bringing a WI-FI Mystery Gift (Available until April 30) the Liberty Pass to a ship in Castelia city.
You can still not receive Genesect, Melodia, and a few other Event Pokemon
In Pokemon black you catch RESHIRAM and TORNADUS In Pokemon white you catch ZEKROM and THUNDERUS Sources : myself
2
There is no legendary Pokemon in Challenger's Cave, only one person who said one used to live there.
Pokemon Black: Last gym leader is male You catch the white legedary Different wild Pokemon Pokemon White: Last gym leader is a female You catch a black legendary Different wild pokemon May be more, but these are just the most obvious ones. Only very minor things, though!
you first have to catch/defeat the legendary pokemon cobalion in mistralion cave you catch virizion in pinwheel forest
You have to defeat the elite four then you can catch the legendary
to catch zapdos in pokemon black you have to have every legendary pokemon
you can catch as many legendary Pokemon but only once unless you have it on the computer
You catch them with a ultra ball
Zekrom in Pokemon White and Resharim in Pokemon Black.
In Pokemon black you catch RESHIRAM and TORNADUS In Pokemon white you catch ZEKROM and THUNDERUS Sources : myself
None
In black you can catch Reshiram and tornados. In white you can catch Zekrom and thunderos.
Yes, Reshiram is Black's legendary. You will not be able to catch Zekrom though.
Well it depends what legendary you mean. There are a lot and it would be hard to tell where they all are.
I put a link to guide on all the legendary pokemon in Pokemon Black in the related links.
Yes, you catch it in the Giant Chasm.