This is a real thing.

Trailer
Wiki page
Anime News Network Announcement, with pictures of the promo stuff
Official Site

Love these mashups/collabs/crossovers - for lack of a better word(s).

Namco x Capcom, Marvel vs Capcom, etc.

Pokemon + Nobunaga's Ambition sounds like a crazy combination though but it'll be awesome if they pull it off.

Is this a Pokemon Tactics game...?

I wish it had been RTK, but I'll settle for Nobunaga.

Googled it up a bit and found this gameplay video.

I've only played the early Pokemons on a GBA emulator so I don't really know how close this is to Pokemon Tactics.

From the trailers I see Pokemon in the Sengoku period. I don't see any sort of empire building game. Other than just having Nobunaga in it, I don't see any link to the Nobunaga's Ambition series at all. It might as well have been Pokemon + Kessen, or Sengoku Basara: Pokemon Heroes.