Where is a Kings Rock located in BW2?
Nuvema Town, Icirrus City (Show Level 50-98 Pokémon to Fan Club Owner)
Hope I helped :)
I got one in Castelia City's battle company. I had a Lillipup with 'Pickup' on my team. He did it for me. And you can always show a levelled up Pokemon to the Fan Club owner to get one.