I was going to bring that up, but I didn't want to look too completely "out there" when thinking up what this all means. But since someone else said it, I was thinking that as well. It's not a lot to go by.
I'm hoping that the plot of this game, with N being a Pokemon using Pokemon to battle, isn't true. Yes, I like plot, but I play video games to play video games. If the plot is too heavy and needs to be explained in long dialogue and cut scenes, it won't feel like a video game. I'd just be reading/watching a movie.
Or it could be a new Pokemon that shares its typing. Which I would still prefer if the Isshu Pokedex had none or very very few previously released Pokemon.