This study explores the mechanical behavior of single-crystal copper with silver inclusions, focusing on the effects of dendritic and spherical geometries using molecular dynamics simulations. Uniaxial tensile tests reveal that dendritic inclusions lead to an earlier onset of plasticity due to the presence of high-strain regions at the complex inclusion/matrix interfaces, whereas spherical inclusions exhibit delayed plasticity associated with their symmetric geometry and homogeneous strain distribution. During the plastic regime, the dislocation density is primarily influenced by the volume fraction of silver inclusions rather than their shape, with spherical inclusions showing the highest densities due to their larger volume and higher silver content. Stacking faults, quantified via hexagonal closed-packed atom populations, are strongly correlated with dislocation activity but exhibit transient behavior, indicating that many faults are swept out or transformed during deformation. This transfient effect is observed in all cases, independently of the inclusion size. These findings highlight the complex interplay between inclusion geometry, dislocation activity, and stacking fault evolution in shaping the mechanical properties of copper. The study underscores the need to account for inclusion morphology and defect dynamics when designing advanced copper-based materials and suggests further investigations into the role of dendrite orientation and distribution to enhance material performance in engineering applications.