What about actually batling a robot? That could be fun. Or a gardner. "Garden mower tom would like to battle"
I've actually thought about a gardener before. Like, they could be carrying a bucket of berries or seeds; something along the lines of that, similar to the breeder trainers in DPPt (which carried a bucket of pokéballs). I can imagine battling old ladies being a gardener since from what I know, a lot of grandma's/old ladies like to garden.
As someone above mentioned, a paperboy would be a nice trainer class. Their line before the battle could be a paperboy saying like, "Extra, Extra!" and perhaps a fact/hint about Reshiram or Zekrom being in the newspaper.
These are all interesting ideas, and I'm eager to see the new trainer classes. :)