With the two recently announced, this has been running through my mind.
Isn't it weird how some National Dex 'mons are only found AFTER the Story ends, on the east coasts of Unova, and there is no way to get there in the Main Story?
Though this probably won't happen due to the fact that everything's supposed to be all-new anyway, the least they could do is add few Previous-Gen Pokemon to the roster. At least in areas where it would make sense, for example:
- Buizel found in areas with rivers, like before Nacrene City or after Driftveil City.
- Sandshrew found in Route 4
- Among other areas like Pinwheel Forest or the Moor of Iccirus having more unique-to-area Pokemon.
...Like I said, this might not happen, and I could simply be speaking this just for an excuse to have Floatzel on my teams, but it makes better sense than just closing off an area until you have the National Dex, leaving a good chunk of the Unova region unexplored.
UPDATE
Now that it has been confirmed that previous Pokémon will be back, what would you like to see in Unova?