Regarding Poochyena and Route 102.
You can control where they appear, to some extent. If you stay on the very eastern (Oldale) or western (Petalburg, with two patches) ends of the Route, there's no one running in the grass in those places. I did some Ralts hunting on the Petalburg side with no problems, though I wasn't trying to chain ATM. Poochyena also appear in 101 and 103, and I've snuck up on no less than a baker's dozen, even having an extra Poison Fang one to consider using someday (I'm using a Thunder Fang one that is now a Mightyena). I'm only missing two Egg Moves but will deal with them later when I have a highly leveled and reliable False Swipe user.