Here is a list of all the rare candy locations in black / white:
-
route 2- HM strength
-
route 3- dowsing machine and HM surf needed.
-
route 13- Gift
-
route 16- HM cut and strength
-
Pinwheel forest- dowsing machine
-
Lostorn Forest- HM surf and waterfall
-
Desert Resort- dowsing machine
-
Nimbasa City- Gift
-
Mistralton Cave- HM strength, TM Flash recommended
-
Chargestone Cave
-
Twist Mountain- dowsing machine
-
Icirrus City- Winter Only
-
Anville Town- Gift
-
Victory Road
-
Abundant Shrine- HM surf
-
N's Castle- In one of the rooms
Source: http://wiki.answers.com/Q/Where_are_rare_candies_in_Pokemon_Black_and_White