Well it is possible to get EV reducing berries, however you will need to mutate them as the only way to get them is to mutate them in the berry field at route 7.
In their berry garden when you let different berries grow next to each other, there is a chance that the berries will cross-pollinate and, within the yield of the Berries, you will find one or more of another berry. If you use the Surprise Mulch, this chance is even amplified.
As for the following berries can be obtained by the following combinations:
Apicot Berry = Kelpsy Berry + Wacan Berry
Ganlon Berry = Qualot Berry + Tanga Berry
Grepa Berry = Aguav Berry + Figy Berry
Hondew Berry = Aspear Berry + Leppa Berry
Kee Berry = Liechi Berry + Ganlon Berry
Kelpsy Berry = Chesto Berry + Persim Berry
Liechi Berry = Hondew Berry + Yache Berry
Maranga Berry = Apicot Berry + Petaya Berry
Petaya Berry = Pomeg Berry + Kasib Berry
Pomeg Berry = Iapapa Berry + Mago Berry
Qualot Berry = Oran Berry + Pecha Berry
Salac Berry = Grepa Berry + Roseli Berry
Tamato Berry = Sitrus Berry + Lum Berry
Source