Dislocation-mediated plasticity in perovskite oxides exhibits strong chemistry dependence, yet the microscopic origins of contrasting plastically deformable and brittle behaviors across chemically similar compounds remain poorly understood. In this work, a Phase Field Dislocation Dynamics (PFDD) framework informed by ab initio generalized stacking fault energy (()-surface) calculations is applied to investigate dislocation core structure and glide resistance in four cubic perovskite oxides: SrTiO(_3), CaTiO(_3), KNbO(_3), and KTaO(_3). Equilibrium dissociation of full ( ) dislocations into collinear (1/2 ) partial dislocations separated by an antiphase boundary is observed across all chemistries, with partial separation distances in good agreement with available experimental and atomistic benchmarks. The potassium-containing perovskites develop significantly wider dissociated cores than SrTiO(_3) and CaTiO(_3), consistent with their lower antiphase boundary energies. Athermal Peierls stress calculations reveal that CaTiO(_3) exhibits the highest lattice resistance while SrTiO(_3) exhibits the lowest, reproducing the experimentally observed ranking of plastic deformability across this perovskite series. Additionally, a two-stage glide mechanism is identified in KNbO(_3) and KTaO(_3), wherein the leading and trailing partial dislocations depin under distinct stress thresholds. These results demonstrate that PFDD provides an efficient and transferable mesoscale framework for systematically linking ab initio fault energetics to dislocation dynamics across complex oxide chemistries.