A lot of people have one, and I want to get one myself.
The easiest and only way on you own is to get a protean frogadier in the friend safari post-e4, but many people breed them, so you could always trade quite easily. Hope I helped!
If you choose froakie as a starter, evolve it into Greninja. Then just breed until you get the ability you like. Again, as tazzie said protean seems to more popular than torrent so your bound to find one on GTS. It's worth getting that ability and all you need us a spot of breeding, trading and patience and you'll get what you're after!
Hope this answered extra enquiries!