From what I've heard, it's just Ash's Greninja with an odd appearance

So did new title confirm pokemon z version due.to.xy anime was.made to co inside.with games so to include z.in to the title means it must be next game right right?

Nothing confirmed a New game name yet. It just hints at it at the moment.

The game could still be called XZ YZ, XYZ etc.

They'll build a whole game around that Pokémon so they better make it interesting...

I wonder if the little blob and the dog are actually Pokémon you can capture, but I doubt it. I think these two are just for the films, and will appear in the Z-Game's cutscenes.

It reminds me of John Carpenter's "The Thing", and I think it could function similarly in the story (without the horrible twisted forms and killing of course).

Like it starts out as a cell, and as it's growing it is mimicking other things. For example, the dog form could be based on Houndoom or Furfrou.

So you see it growing in cutscenes, but you're only able to catch it once it is in his 50/100% form, which is a form change and neither the little blob nor the dog are actually Pokémon you can catch.

I think at this point it is pretty obvious that the next game is Pokémon Z.

(Bad Perfect Cell joke...)

Judging by the blue and red in Zygarde Perfect's wings, I'm guessing he needs to absorb Xerneas and Yveltal's energy to become this form?

(Cue cricket SFX...)

Bad jokes aside, yeah, this says that Pokémon Z is pretty much near confirmed.

In fact, I wouldn't be surprised if it's currently in development right this moment and it's officially announced in next month's issue of Corocoro with a January/February worldwide release date, well BEFORE Pokken Tournament or Pokémon GO.

I can't wait to break into Area 51 to catch Deoxys...it's gonna be great~!

Some users on Reddit have pointed out that Zygardes multiple forms may further advance the Norse Yggdrasil theme that Xerneas and Yveltal had going on. Previously, Xerneas represented the stags Dáinn, Dvalinn, Duneyrr and Duraþrór, Yveltal represented Veðrfölnir and eagle and Zygarde represented NÃ*ðhöggr.

Now, Zygarde 10% and Perfect could be based on Fenrir and Hel, respectively.

Hel? That's one Hel of a stretch.
Fenrir is kind of pushing it, too, though I may just be a little biased since I associate Fenrir with the end of the world, not just a weakened state.

Fenrir makes sense, but Hel is a woman and looks nothing like the Perfect form.

I'm thinking that's gonna be the case to some extent.