Someone posted it in a different thread but is this the one you were talking about ?
I'm like 80% sure I've seen Froakie's final stage somewhere a long time ago, before Frogadier was released...
I really like these final stages though! Fennekin's final stage looks downright epic!!! :3 I hope when Braixen evolves it looks something like this leans more towards a unisex look but still keeps a cool posture. Also, if the staff was longer it'd be more appealing too..BUT IT MOST KEEP THE FUR CAPE!!
Froakie's final is okay, I like the colour but he looks a little stiff.
But yeah this is most likely fake due to the fact they look too small to be final starters. EVERY final stage starters are really big or tall, whereas these guys look like those small powerhouse (e.g. Lucario, Breloom, Eeveelutions etc.)