Your question is so confusing that there's no point in answering it.
If you're basically asking if a Pokemon can gain benefits from reducing EVs and retraining them, then the answer is no. I think you don't understand EVs fully and that's why your question is so confusing. You should see EVs as something separate to the actual stat, something that's a "top up" to the stat and not part of the stat. That means that the actual stat never actually decreases when you use berries, it's just the EVs.