Probably the best system devised for landing on a pitching deck is the Bear Trap developed by the Canadians and used on all of the Spruance Class Destroyers in the US Navy. In this system the helicopter is winched down to the deck. The American system further expanded on the design and uses the bear trap as a trolley and it drags the helicopter into the flight deck hangar freeing up the flight deck for the second helicopter.
The system as originally designed, (when I was involved), would compensate for pitching and heaving of the flight deck. When the stern went down the cable would be paid out and when it went up the cable would be reefed in so that the helicopter would be independent of the ships motion. In each case the cable would be reefed in more than it was paid out and eventually the helicopter would be pulled down to the deck.
