This artwork is really cool. It's so different to all the others.
I'll take Chespin by the way, exactly because you can't say, what he exactly is.
There already are firetype foxes and watertype frogs, but nothing like chespin.
Yeah, I also was kind a shocked But I got used to it. We all just expected something different.
And he is based on a Paladin (Quilladinaladin) so maby his final form will be a noble knight or something like that :3
It's an obvious theory:
Fennekin/Braixen: Is going to be psychic and uses a wand. It's a mage.
Froakie/Frogadier: It is a Rogue. That also tells us the German name "Amphitzel" which contains "Spitzel" which is a word for spy.
Chespin/Quilladin: It is a Paladin. The 2nd name tells it and it's an armored Pokemon.
So I think the theory of them representing the RPG classes is what they thought for creating them.