How do you get a exp share in Pokemon black 2?

In order to get Exp. Share in Fire Red you need to have known the move "Cut" and gotten the "Poke Flute" to wake Snorlax. Once you have beaten the gym in Celadon City and have caught 50 species of Pokemon you have to go to Fucchia city and walk east toward route 15. The building that connects the towns together has a second floor where Prof Oak's Aide will give Exp. Share to you.