Courtesy of Nintendo Life:
You can also use one of your Game Vouchers for it.
If you pre-purchase and pre-load Luigi's Mansion 3 right now, you'll also receive double My Nintendo Gold Points – so that's 600 in total. This is a limited time offer and will end on 30th October, prior to this game's launch on the 31st.
You can also use one of your Game Vouchers for it.