Despite intensive investigations, the comprehension of the mechanisms ruling the interplay of charge doping, electron–phonon coupling and dynamic screening in supported graphene remains elusive yet. Using a combination of surface-science spectroscopies, we have studied these phenomena for graphene on both Pt-skin-terminated and nickel-oxide-skin-terminated Pt 3 Ni (1 1 1). Graphene epitaxially grown on the (1 1 1)-oriented Pt skin behaves as a charge-neutral graphene/metal contact, exhibiting a reduced coupling of the out-of-plane optical phonon with Dirac-cone electrons. Conversely, p-doped graphene/Pt (1 1 1) exhibits giant Kohn anomalies arising from the electron–phonon coupling. Upon oxidation, the Pt skin of Pt 3 Ni (1 1 1) evolves into a nickel-oxide skin, which results into a p-type doped graphene sheet. The plasmonic spectrum shows dramatic changes when going from a graphene/Pt-skin …