Tornadus is probably the best candidate for your Master Ball. Because it is a roaming Pokemon which can flee from battle, it's worth it for that assured capture. While it may not be as strong as Kyurem, Kyurem can nonetheless be captured the usual way with a bit of patience.
Yes
Just be paitent and catch it with a pokeball!
you cant catch it you have to get it from a friend that has Pokemon black or get from a gts tradeYou can't the only way to get Tornadus in Pokemon White is by using cheats or by trading it from Pokemon Black.
With a pokeball
You catch Cobalion with any Pokeball that is possible to catch it in.
A lure ball :)
throw a pokeball at it
you can only get tornadus in black or you can trade.
a quick ball or a master ball
GS ball
The Master Ball is the strongest Pokeball as it guarantees a catch without fail when used on a wild Pokemon.
Tornadus is probably the best candidate for your Master Ball. Because it is a roaming Pokemon which can flee from battle, it's worth it for that assured capture. While it may not be as strong as Kyurem, Kyurem can nonetheless be captured the usual way with a bit of patience.
a pokeball
Ash used a lure ball.
any kind, i used a pokeball
I recommend the master ball