Me and a few friends were gonna do a coop ng+ run but idk how to record switch gameplay anyone know how?

Also what difficulty does a NG+ coop run have to be played in?

You'll need a capture card

NG+ Coop boards have no difficulty restriction currently so anything but Friendly will handicap you a bit. Cobermai is correct in that you will need a capture card and computer to record or stream your gameplay from the Switch since there aren’t built in streaming apps like Xbone/PS4.