Can I catch a vigoroth and add it on my team in Pokemon Black 2??

Question

i want a slaking for the Pokemon league

Answer 1

Good news, Vigoroth is available in the games! :D

Bad news, it's post game. Vigoroth (and Slaking, on rare occasions) can only be found in the Pinwheel Forest, which is only accessible after beating the league.

You can always trade from another, completed version of either Black 2 or White 2, but for the moment I'm sorry, but Vigoroth is not available at this point. Sorry.

Hope I helped. :)
Source: www.serebii.net/pokearth/unova/pinwheelforest.shtml

Answer 2

Like Indigo said, it's post game.
BUT, you can also use Global Trade Station or Poke Transfer to get it from a Gen 3 game by first Migrating from Gen 3 to Gen 4, then using Poke Transfer to move the Pokemon from Gen 4 to 5.

:) hope this helped.