Core-shell nanostructured catalysts possess a novel architecture where a major portion (core) of the nanoparticle is composed of cheaper materials such as Cobalt, Palladium, Copper, etc., with only a small portion (shell) being the expensive Platinum (Pt) thus enabling the reduction of Pt loading in the catalyst layer. These core-shell nanocatalysts are known to exhibit better mass activity than their monolithic counterparts. In this context, tuning the core can result in a change in both mechanical and geometrical properties, and in turn, can influence the stability. Specifically, designing an interface with surface stresses that makes the structure of the nanostructured catalysts resistant to dissolution would be pivotal towards achieving enhanced durability in PEFC systems. The lattice mismatch between the core and shell is a key intrinsic parameter that governs a transition towards a thermodynamically metastable state. In this work, the mesoscale underpinnings of such metastability on the underlying electro-chemo-mechanical coupling and the resulting influence on degradation-performance interactions will be analyzed. Further, the role of molar volumes and elastic moduli of such core-shell pairs on the evolution of stress states and degradation landscape will be investigated. Design criteria including the influence of shell thickness in protecting against degradation will be delineated.