6th Gen Who is the defining Gen 6 Pokemon?

I'd probably say Sylveon, it just screams Gen 6 since:
1. It has the Fairy typing
2. It evolves using the Poke Amino feature

This is a hard one for me. I'd say that basically any mega evolution could qualify, as well as Greninja, Klefki and Legendaries. So my answer is rubbish, but it's the best that I could do.

Xerneas. Being the most dangerous sweeper to grace competitive Pokemon since Generation I Mewtwo, it is the epitome of Generation VI's 'power creep'.

i reckon greninja but since everyone else has said that, maybe sylveon

fairy typed being introduced was a pretty big thing and since it's already part of a line that so many people know and love, i would say it's a decent shout

I think Sylveon

At first I'd of said Fennekin due to it's popularity. But now probably Greninja or Zygarde :P