With the presence of robust flat band in YCo₅ which has high Magnetocrystalline Anisotropy Energy (MAE) among itinerant magnets, doping of hole to the Y-site with smaller ionic radii has shown significant change in the MAE. This system is found to be pseudo two dimensional ferromagnetic in nature under density functional calculations employing GGA+U exchange potential in WIEN2k. With hole doping the original flat band is extended to whole Brillouin zone. In addition to it the Fermi level is shifted because of it. The exchange interaction is evaluated for pristine and doped system using Heisenberg Hamiltonian and the Curie temperature evaluated was close to the experimental results. This enables to control the filling of flat bands upon doping, resulting in novel feature of band engineering.