For the next generation, they need "wanted pokemon" filters.
That, and that you could search for what people want. Like if you had a spare Chimchar, you could search for people that want a Chimchar for their pokemon.
Yeah, it's really annoying when you're searching for something simple like an Aipom and everyone wants a Palkia. x_x
But I've also found many good deals with enough searching. ;)