We present simulations of Pockels materials based on nonlinearities arising from intersubband transitions (ISBT). To elevate the Pockels coefficient to the order of nm/V, the ISBT resonance is tuned close to the operation point. This comes at the expense of increased material losses due to quasi-resonant operation. Such Pockels materials are of high interest for implementation in plasmonic modulators. In these modulators the higher material losses do not significantly impact the device performance, as overall losses are dominated by plasmonic waveguide losses. With this approach, voltage-loss-length (V_πLα) products on the order of ∼15 V dB may be achieved with plasmonic losses. Such efficiencies are comparable to those with photonic modulators. The Pockels effect coefficient calculations have been performed using self-consistent Schrödinger-Poisson simulations with consideration of many-body effects. Furthermore, we investigated the influence of RF field screening and surface roughness on the efficiency of the ISB transition-mediated Pockels materials.