Most likely the moving plane will be assigned some if not much of the fault, but it's entirely possible the parked plane and ATC could be assigned some fault as well. There are certain positions planes are assigned to taxi to and stop. If the non-moving plane didn't pull up far enough to the correct position and was into the taxiway, for example, it could be assigned some blame. Theoretically, if all planes are in the correct positions and ATC is doing its job, one should be able to taxi as instructed without having to pay attention to where others are.