EV Reducing Beries:
HP- Pomeg Berry
Mutate a Lapapa Berry and a Mago Berry
Attack- Kelpsy Berry
Mutate a Chesto Berry and a Persim Berry
Defense- Qualot Berry
Mutate a Oran Berry and a Pecha Berry
Special Attack- Hondew Berry
Mutate a Aspear Berry and a Leppa Berry
Special Defense- Grepa Berry
Mutate a Aguav Berry and a Figy Berry
Speed- Tamato Berry
Mutate a Sitrus Berry and a Lum Berry
For more information click here.
Hope I helped :)