A lot of my EVs were wasted on Snorlax, because he has a reasonably high Speed (don't ask; I don't even know how). Anyway, I'm in Laverre City right now and am wondering if I can get my hands on those berries.
You obtain them by mutating berries, which basically involves planting specific types of berries next to each other, and then it has a chance of giving you a certain EV berry (and some others too).
Untill now we know the following combinations:
Mago + Iapapa = Pomeg
Chesto + Persim = Kelpsy
Sitrus +Lum = Tamato
Aspear + Leppa = Hondew
Aguav + Figy = Grepa
Oran + Pecha = Qualot
(and some other non EV berries, not listed)