>>24775386This was drawn by Muneo Saito, who did the designs for Entei, Raikou, and Suicune.
This picture (and
>>24775468) was shown off at a character design-based art course. It was never stated be related to their Pokemon work.
Bulbapedo and other places just throw it around as a beta design because it uses the same sort of cloud-thing on its back as the legendary beasts, but it could just as likely be something similar the artist drew years later.