Serebii from SPPPosted 10/8/2012 1:11:34 PM(edited)
If memory serves, it's in the building opposite the Gym in Castelia City --- Serebii from the amazing Serebii.net Your #1 Source for ALL Pokémon Games & Anime info as the top online Pokédex & Attackdex!
Tifay(Topic Creator)Posted 10/8/2012 1:15:00 PM
pkmnpkmnPosted 10/8/2012 1:17:04 PM
All you get for the meaningless sidequest is a rare candy --- The Offical Groudon Oof the POkemon Black and White 2 Boards.