Yes, these berries reduce stats:
#21 Pomeg Berry (HP)
#22 Kelpsy Berry (Attack)
#23 Qualot Berry (Defense)
#24 Hondew Berry (Sp. Attack)
#25 Grepa Berry (Sp. Defense)
#26 Tamato Berry (Speed)
Berries aren't common in Black/White so you may not be able to get these ones. However, when the Dream World is opened, you are able to plant and grow berries so you should be able to get plenty of them.