Question

At the stadium at Nimbasa city in pokemon black, ive heard you can battle somebody and get a rare candy for winning. I versed everyone and beat them and I didn't get a rare candy. I checked every where inside my bag and there was none, please tell me where to find the person or if nobody gives you one.

Answer 1

Well, that's quite simple. It's all about luck, in fact. Before I start, you can get as many Rare Candies as you'd like, you really just rely on your good luck to find the same Trainer as many times as you wish.
She is called Nurse Aide Leah and shows up in either Big Stadium or Small Court.

Source

Answer 2

Have you been to both stadiums? There are 2 in Black. Small Court and Big Stadium. A Rare Candy is definitely available to receive in Big Stadium, but if you can't find it, you probably already got it. Not sure which person, but there is definitely one in Big Stadium

Comments

A Nursery Aid will give you one after defeating her.