Even if this is an entirely new Pokemon. Mewtwo is still far, far more likely than your Lyn will ever be for Smash 4.
The fact is that Mewtwo is Number 1 most wanted character for Smash 4. Number 1. No one is more wanted than him in Japan, and only Mega Man is more wanted than him in the West.
Mewtwo is still getting a lot of screentime with the new movie, and Sakurai has solid instincts in general. Worse comes to worse, I could see Mewtwo simply "transforming" into this Mewzora form in Smash 4.
The Japanese fanbase will riot if that don't get their single most wanted character.