You find him in a cave.
Virizion is for pokemon black. You can find Cobalion in white.
You find Cobalion on Mistralton Cave.
He is in a cave!
Pinwheel forest, after catching cobalion in the guidance chamber.
You get it at Mistralton Cave
Yes, Cobalion is a legendary pokemon.
You can find Cobalion in Mistralton Cave and once you do. You might want to save and soft reset every time if it isn't. It is hard to find though.
In Mistralton Cave
you find him in mistralton cave.
In Pokemon White, you can find virizion in a clearing in pinwheel forest that isn't accessable untill you catch Cobalion.
You can get Cobalion, Virizion, Terrakion, Kyurem and Zekrom (only in White).
Terrakion in Victory Road.