The Sinnoh region tends to be the second most popular after Kanto and its OG 151 so it would make a lot of sense for Pocket to head there next if it's going to try and retain as much of its player base as possible
While WotC keeps some booster fun in the play boosters, the dressy showcase cards are significantly more common in collector boosters
Collector Insight Reverse Holo cards are more common because every pack in modern sets is guaranteed to contain at least one Reverse Holo in the reverse slot
1 Trainer Super Secret Battle Not a Pokmon, but an official card
It was not hard to see that Atla Palani, Nest Tender could do one of the most powerful things to be done in Magic: cheat on mana costs
I believe Ethan Fleischer, the lead designer for Oath of the Gatewatch , made a few cards in Battle for Zendikar design, but the focus was too much on how the Allies were losing to make the five-color commander feel right