You get a Gen 1 starter at the beginning of the game and their final forms have mega evolutions now.
The transference system from 5 to 6 is a cloud storage thing that costs a subscription fee to use. Part of its purpose is to crack down on illegal and hacked pokémon. Hope Game Freak doesn't make any mistakes with the more obscure reaches of pokémon learnsets, from FRLG tutors and events and such... technically any gen 4 or earlier pokémon can learn a moveset consisting of any combination of gen 4 moves, a gen 5 move, plus any gen 5 move they can learn legitimately, from the Mimic Glitch. But of course that won't be accounted for.
I'm only disappointed at how much attention past generations are getting, again. I think gen 5's strongest point was how recklessly it left everything behind. Almost everything got new toys in the form of hidden abilities, but as far as hype went, it was all new. Not that the new gen 6 pokémon are disappointing me. It's just the opposite. I want to see more of them, and not evolutions and pre-evolutions of old ones. A new pokémon was seen in a screenshot today but it looks very much like a pre-evolved form of Absol... Other than that it's been all about mega evolutions, and so far none of them have been given to gen 5 or 6 pokémon.
So, I'm not going to be using the gen 1 starter, myself. I'm really super-tired of Kanto to the point that even using one of the starters again is more retread of it than I need.