These kinds of "micro bullies" in particular just look like squashed pitbulls. American Bulldog, APBT, etc. They're not really "bulldogs" at all.
What I want to know is have they had smaller dog breeds bred in along the way to enhance the small stature or is that solely a result of selective breeding and inbreeding over years? And secondly, though these dogs aren't much of a physical threat, do they have the traits that other bull and terrier breeds have such as gameness, or are they so genetically warped that kind of behaviour is muted? Are they neurotic at all? These trashy breeders harp on about the look but what about behaviour and temperament?