Analysis of the app's files show that the devs left a mostly-functional BB3 that currently can't appear on AI characters or from move relics. As to why it's not in the game, it's hard to tell. Right now it appears that it was deemed too weak to be a BB3 and might be re-added in the next patch. Picture below. Hopefully we see it in the wild soon, preferably with a very quick charge rate and higher damage to bring it in line with the rest of the AI's BB3 options.