Question

I know your mom buys you the ones that reduce super effective moves. And the basic ones like Oran Berry are around. But what about other berries, like the EV reducing ones?

Answer 1

There are some rare obtainable only in events - however, many kinds of berries may be obtained (PokéWalker, Shards collectors...etc)
So, the answer is no.

Answer 2

You can get some berries by exchanging shards with the man in Fuchsia city and in violet
http://www.serebii.net/heartgoldsoulsilver/shards.shtml