Like if you defeat Volcarona and then defeat the Eilte 4, will it come back at a higher level like the Swords of Justice?
In Pokémon Black and White there is only one Volcarona at Level 70 in Relic Castle and if you defeat it you will not have another shot to capture it (that's why it's best to save the game before you interact with Special or Legendary Pokémon kids!)
But in Pokémon Black and White 2 despite there still being one Volcarona if you defeat it on the first encounter, you will get another shot to capture it when you have defeated the Elite 4 and Champion and have been entered in the Hall of Fame. On the first encounter Volcarona will be at Level 35 and on the second encounter it will be at Level 65.
Source
No,But it is somewhat of a legendary....I think Source:http://www.pokecommunity.com/archive/index.php/t-302604.html