I know I've seen them somewhere, but I can't remember where. Taking a quick look at showdown/smogon, they missed the SM Ace Trainers. I think whoever did the gen7 sprites might have done them, but they never got added?
smogon's not exactly known for it's artists. Sadly I can't remember the name of the guy who made most of the gen7 trainer sprites, but I know he had a DA. I'm not going to lose sleep over it, but if I happen to find gen7 trainer sprites I'll let you know.