How cool would it be if you could use HMs to teach your trainers special moves? Maybe then there would be a special trainer battle arena where their Pokémon wait on the sidelines and watch.
There IS trainer combat in Pokemon Tabletop United, if you’re into tabletop games. It’s an awesome concept. :P
All jokes aside the human repel is a sorely needed item right now. It would have to be a expensive item for the conveinience of course.