The Yellow Devils have been an interesting enemy throughout Mega Man's history. Most of which by being a pain in the butt. The overall design of them has been similar as you can tell from the Yellow and Black Devil. The Black one being from Mega Man X 5. The one in the middle is Alpha aka Proto in Japan. It came from Mega Man Battle Network 3 and I'm not entirely sure if if Alpha is considered to be apart of the Yellow Devil family but he sure as heck looks like it does.