We present an application of Eliashberg theory of superconductivity to study a set of novel superconducting systems with a wide range of structural and chemical properties. The set includes three intercalated group-IV honeycomb layered structures, SH₃ at 200 GPa (the superconductor with the highest measured critical temperature), the similar system SeH₃ at 150 GPa, and a lithium doped mono-layer of black phosphorus. The theoretical approach we adopt is a recently developed, fully ab-initio Eliashberg approach that takes into account the Coulomb interaction in a full energy-resolved fashion avoiding any free parameters like μ^∗. This method provides reasonable estimations of superconducting properties, including T_C and the excitation spectra of superconductors.