This controller would be only accessible by users who are members of the PowerUser role or the ControlPanelUser role

This controller would be only accessible by users who are members of the PowerUser  role and the ControlPanelUser role simultaneously

This controller will not be accessible neither by users who are members of the PowerUser role, no by members of the ControlPanelUser role because this is wrong syntax

This controller would be only accessible by users who are members of the role with the next name: PowerUser,ControlPanelUser