At a minimum, a VASP run will require the following files: KPOINTS, INCAR, POSCAR, and a POTCAR file.
https://cms.mpi.univie.ac.at/vasp/vasp/Simple_bulk_calculations.html
The POSCAR consists of several portions.
The selection of the POTCAR. I only use GGA-PBE and LDA potentials. Other than looking up previous calculations in literature, I've adopted the selection of potentials as used by materials project initially for simulation.
[1] https://materialsproject.org/wiki/index.php/Pseudopotentials_Choice