EV Clearing NPCs are a good Quality of Life feature that the modern games have incorporated for a reason. Most players don't like grinding massive amounts of EV reducing berries without being able to buy them and would rather grind out EVs as the process is generally more mentally stimulating...
I have always had a hard time finding a banking system in Pokémon essentials, but I was able to come up with a pretty simple banking system for my fangames. Its not fully scripted, so you will need to define a few variables for it to work. But afterwards you can change dialogue and other things...