The performance of functional nanocatalysts can be extended by integrating multiple types of metals into well-designed nanoparticles. A porous multimetallic shell grown around high-quality monometallic seeds significantly enhances the availability of active sites. Here, tetrametallic core/shell nanoparticles (Au@mPdPtIr) featuring micro- and mesoporous shells are synthesized with strict control over the overall particle morphology. To reveal the impact of the core nanoparticle morphology on the optical, structural and electrocatalytic properties, tetrametallic particles are prepared using gold cores with different shapes but identical volumes and surface chemistry. Our general synthetic approach ensures the successful and reliable synthesis of porous trimetallic shells around the cores, keeping the final atomic composition of the different multimetallic particles identical. The results clearly highlight the significance of the core morphology in the catalytic performance and the superior activity of symmetry-broken core/shell particles in heterogeneous as well as electrocatalytic oxidation reactions. These can be attributed to the fine structural details of the deposited trimetallic shells and their influence on the charge carrier transport between the multimetallic particles and the organic test molecules. While all nanocatalysts show excellent morphological robustness, the optimal morphology also depends on the reaction type and conditions of the specific reaction.