Depends on what department you belong to.
For Engine room personnel it would be qualifications and experience from diesel/electric and hybrid propulsion, since most of the wind support vessels, now and in the near future, is/will be of that type.
For bridge (Wheelhouse) personnel DP certification and experience is required. (Most SOVs are DPII or III)
For Deck crew it would be to have some additional qualifications to AB, like Crane Operator, Rigging and Slinging Certificate, FRC and/or HLO Certificate etc.
But for ALL and most of all, the ability to adjust to a different type of work environment and willingness and ability to learn as the jobs and technology change over time.