Well, I literally just did it and got a Shiny Poochyena within 25 encounters.
> I used the DexNav (on Route 101) and kept encountering and K.O.‘ing Poochyenas. Sometimes I also caught them if they had nice moves.
So, YES. YOU *CAN* CATCH THEM.
> Even when the DexNav said “It couldn’t be found nearby. Try looking in a different spot!” I just pressed search whilst moving to a different patch of grass. I’d do this over and over until finally another Poochyena showed up.
So, YES. YOU *CAN* WALK AROUND WHILST CHAINING and YES, YOU *CAN* KEEP GOING EVEN IF THE POKEMON ISN’T FOUND.
And that’s pretty much it. That’s how I did it.
> Use Dexnav
> K.O. or catch, up to you. I don’t know if running works or not too.
> If no Pokemon is found, move to another spot and keep trying until it shows up again.