Perfect pitch is in no way necessary for this. Interval listening is sufficient. The additional benefit of perfect pitch would be, that your friend would know t

Perfect pitch is in no way necessary for this. Interval listening is sufficient. The additional benefit of perfect pitch would be, that your friend would know the basic key of the tune without first playing one note on the piano. For example, I don't have perfect pitch, but I can play along with any pop song immediately, without sheet music and without knowing the piece. I just have to press a few keys on the keyboard to find the root note.