Deino before the E4
Solution 1:
By Googling "deino bw2" and following the first link, I can tell you that Deino is not found in the wild in Pokémon BW2. However, Zweilous can be found on the 7th floor of the Victory Road and at the entrance to N's castle. Clicking on the Pokéarth link then reveals that the BW2 Victory Road doesn't have 7 floors, but Zweilous can be found on the third floor and the entrance to N's castle, which is this area:
