Answer 1

In the Plasma Frigate the second time you enter, after you beat Marlon
Source: http://pokemondb.net/pokebase/98559/how-do-i-get-the-electrizer-in-white-2
Hope I helped!

Answer 2

You can find it in the Plasma Frigate the second time you enter, after you beat Marlon.

Comments

U done the exact same thing as as me I just didnt type the first part

Answer 3

You find it in the B1F of the plasma frigate on one of the left rooms during or after your second visit.
Source:http://bulbapedia.bulbagarden.net/wiki/Electrizer#Electirizer