Laves phases are topologically close-packed structures that form in many alloys and serve as fundamental building blocks in complex intermetallics. A thorough comprehension of the plasticity in Laves crystals would facilitate knowledge transfer to numerous complex phases and composites. In this study, the mechanisms of motion of synchro-Shockley dislocations were investigated using atomistic simulations. We demonstrated the thermally activated nature of synchro-Shockley dislocations, providing insight into the atomic origin of room-temperature brittleness in Laves phases. We explored how vacancies and antisite defects assist kink nucleation and propagation, which are crucial for dislocation mobility in such material. Furthermore, using ab initio calculations, we revealed the effects of structure and composition on the mechanical properties and deformation mechanisms of Laves and µ phases. Our findings shed light on how temperature and chemical composition affect the plastic deformation induced by zonal dislocations in Laves phases and provide avenues for tailoring the mechanical properties of complex intermetallics.