If you study piano at uni (or another instrument), you will be surrounded by people who can also play and know ALOT, so IMO you would need to be perfect with scales, if they ask you to play, c major, b minor, b major, b flat major, a minor, e major arpeggio dim. etc. whether, piano, forte, crescendo up and diminuendo back you have to know them, without any stops, pauses, uneven playing, and they have to be played at a fairly fast speed, probably 100 bpm 4 notes per beat minimum. Also good octaves, sixths etc. In your pieces you have to take note every detail, phrases, everything!! Your sightreading must be pretty good, you wouldn't have to sight read like any mozart sonatas or anything but anything they give you, you must be able to play it at a moderate speed with not many mistakes. Plus the basic thoery skills of course, composition/harmony/chords/cadences/ Oh and i hate this but Aural, Clapping, Singing Ear skills.