The heat transfer through Riga surface associated to Robin condition and transient effects is an interesting topic. The primary objectives of this work are to model a heat transfer problem for vertical Riga surface using hybrid nanocomposite properties, along with thermal radiation, mixed convection and unsteady effects. The problem governs the flow transformed into dimensionless form with the help of similarity transformations, and enhanced properties of nanofluids. The model novelty falls in the development of superior tetra nanofluid class and its comparison with traditional classes (ternary, hybrid and simple) by integrating the aforementioned parameters. After that, the RK numerical scheme is applied for the solution and the results plotted by varying the physical parameters (thermal radiation, Biot number, unsteady and mixed convection parameters). The findings reveal that Biot number from 0.2 to 0.8, thermal radiation parameter from 0.1 to 0.7, and nanoparticles concentration from 1 to 4% promisingly increases the temperature with maximum increase in tetra nanofluid case than ternary, hybrid and simple cases. However, strengthening the mixed convection ( δ ) from 0.01 to 0.04 and magnetic effects due to Riga surface controls the temperature significantly. The skin friction against ϕ1 from 1 to 4% shows variations from 1.0214 to 1.0051 (tetra), 1.1290 to 1.1179 (ternary), 1.1385 to 1.1304 (hybrid), and 1.1786 to 1.1740 for traditional nanofluid. The comparative heat transfer gradient improves for strong Biot number effects and enhances from 0.2707 to 0.440 (tetra), 0.1233 to 0.3915 (ternary), 0.1150 to 0.3671 (hybrid) and 0.1109 to 0.3536 for simple nanofluid with promising increase in tetra nanofluid. The comparative findings reveal key role of tetra nanofluid for heat transfer while the less thermal efficiency is investigated for other classes.