This paper presents an evolution method used to modify the morphology of humanoids to make them more efficient in a specific direction of walking. Starting from the NAO's model used in the 3D Simulation Soccer League, the walking specializations are based on 5 to 8 parameters that are being evolved. A black-box optimization process is run and guided by a decision-making function that defines the outcome of the humanoid evolution process. The simulation results lead to four optimized morphological profiles, each of them specialized for either forward , or lateral, or diagonal walk, or in-place turn respectively. These results could be used to build heterogeneous humanoids inside a team of soccer players.