We have recently integrated a social login via Google. If you want to register you can simply use your existing Google account. As we said we’ll make it as easy and as comfortable as possible for you to join our Pokémon Go trainer community, we will also provide other social logins, e.g. Facebook, Twitter.
They will follow soon. Meanwhile you can register via Google to the Pokémon Go trainer community, get social and tell your friends about this platform 😉