Volcarona is a special pokemon that you will only encounter once in Pokemon White.
After you get the National Pokedex, return to the Relic Castle and you’ll be able to encounter Volcarona near the end of the catacombs.
Volcarona is level 70 when you encounter it and has a low catch rate, so come prepared with high level pokemon and a lot of pokeballs.
Alternatively, you can evolve a Larvesta into a Volcarona at level 59. The only way to get Larvesta is to talk to the person in the house on route 18 to receive a Larvesta egg. You must have room in your party for the egg or you won’t receive it.

Kathie September 1, 2012 at 4:03 pm
You can also try using Net Balls since Volcarona is a bug type. It worked well for me.^^
hunter April 12, 2012 at 8:45 pm
would a quick ball help?
i tryed 30 times to get vol its hard!
Essie March 31, 2012 at 5:21 pm
I used fly, and dive. Two pokeballs later and I caught it.
Star May 15, 2011 at 11:10 pm
I used surf and caught it with a pokeball on the first try. The poke ball shined for some reason and Volcarona didn’t even struggle to get out of the ball. Weird.
john June 3, 2011 at 5:37 pm
u probably got a ‘critical catch’. I know people say its a myth but its real, at least in pokemon white and black. When it happened to me, the ball shook a bit before hitting the ground and it only rolled once and the pokemon was caught. You’re very lucky to have a critical catch in a situation with valcarona.
Chris July 18, 2012 at 2:20 pm
I got that with thundurus I still can’t catch this motherfucking pokemon damn him thanks
nathan May 1, 2011 at 5:17 pm
awesome!!!!!!!!!! it has taken me tons of times.
winsten August 2, 2011 at 5:59 pm
how many trys did it take you
Misty March 24, 2011 at 3:26 am
i got it on the first go with one surf hit then used an ultra ball ^^