So, uh, apparently the number of new pokemon is...
uh...
low.
As in... 70ish.
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On a slightly unrelated note; I for one think that Nintendo are being marketing geniuses with this game.
They're appealing to old players with things like 'Not limited to just this region's mons' like B/W was. And especially keeping older players on board with Charmander/Squirtle/Bulbasaur.
But they are, at the same time, appealing to new players with new mechanics, like Mega Evolutions, while still adding new mons. What was one of the first things they revealed? A new Eeveelution. And that was how they revealed the new type, a new mechanic that may have driven away purists. But they did it through Eevee. To connect with the purists and those who are used to the way things work while adding something new.
Mega Evolutions give something for everyone as well. We know something from each gen is getting one. While the number of new mons is apparently low, there's a lot more to explore. Also, apparently, despite the low number of new mons, the regional dex is MASSIVE. Again 'something for everyone'.