Squaregonial jaw with gonial angle will leads to:
In the horizontal growth pattern, there is a tendency for the mandible to rotate upward and forward. The lower anterior facial height is relatively short with a tendency for deep bite. 
Such persons have a squarish face, a low mandibular plane angle, well-developed jaw elevators, increased biting force, and broad dental arches.
Ref: Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities THIRD EDITION
Om P. Kharbanda, pdf no 670
Low mandibular plane angle
Increased mandibular plane angle
No change
Low or increased mandibular plane angle