I really don't think it's alternate form of any other Pokemon. If so, it would be wrong to call it "new Pokemon". It's either Arceus or an entirely new Pokemon. I really think it would be odd to reveal both Arceus and Shaymin in one movie. Who will be the star of the next movie? Cresselia and Heatran are too uninteresting to get their own movie. I think the Pixies will appear in the anime only as well.
I think the only plausible answer is that the mystery Pokemon is a 5th gen, one that is probably basic to, like many people posted before, provide comic relief or just appear in the background.
Having Giratina, Shaymin, Dialga, Regigigas AND Arceus in one movie would be too much. And having Arceus appear as a cameo would be a waste...
I think the only plausible answer is that the mystery Pokemon is a 5th gen, one that is probably basic to, like many people posted before, provide comic relief or just appear in the background.
Having Giratina, Shaymin, Dialga, Regigigas AND Arceus in one movie would be too much. And having Arceus appear as a cameo would be a waste...