Recently, it has been widely recognized that control and mechanical systems cannot be designed separately due to their tight interdependency. However, there still leaves much to be understood about 1) how the relationship between control and mechanical systems should be; and 2) what does the well-balanced coupling between these two systems bring to resulting behavior? In light of these facts, as an initial step toward this goal, this paper intensively discusses the coupling from the view point of the temporal contribution of control and mechanical systems to the resulting behavior, employing a simple pseudo-passive dynamic walking biped as a practical example. Preliminary results support that discrete control strategy, which effectively exploits diversity of motion trajectory, enables to enhance the robustness against external perturbation. To the best of our knowledge, this has never been explicitly discussed so far. Based on these results, this study proposes a Pulsed-CPG that allows us to achieve the appropriate coupling between control and mechanical systems as well as to change the brain-body interaction adaptively according to the situation encountered.