When I ask that I mean when they have occa berries and passho berries. you just cant get them. Are they there for a challange?
Actually those items are available through Join Avenue. They have also been available in previous games, and may be obtained from the Dream World, events or over trades.
However yeah I suppose they're there for the challange and they reduce the power of certain super-effective attacks which only really makes you rage that its going to take another turn to beat them =) ~ also GameFreak loves giving little gimmicky items that have no use in Competitive battling just to annoy you
They have the items because: 1: to make it more challenging. 2: So they have a variety and not just boring, usual items [cough, leftovers, cough]. 3: They are computer players! It's not like they are actual people! I hope this helps!