Verified answer

Listen to Mary and Oak on the radio every day to hear what your mass outbreak is. Mine has been ralts every other day for a week! Once you at least see one (battle it, even if you don't catch it), it will then be in your pokedex so you can trade for one on the gts.

So, yes they will appear on Rt. 34, but only on their mass outbreak days. You just have to listen to the radio/pokegear every day and it will turn up soon. The mass outbreaks are randomly selected.

Ralts Pokedex

You'll need a trainer's number so they can tell you when it swarms.

That's about all I can tell you...sorry!

http://www.serebii.net/pokedex-dp/location/280.sht...