https://www.cnet.com/news/you-can-play-fortnite-for-switch-without-nintendos-paid-online-service/

Nintendo formally unveiled its new Switch Online service on Thursday, and one of the more notable details was the need to subscribe to the service for multiplayer games. Detailed in one of the FAQs, however, it specifically mentions the super popular shooter Fortnite as one of the games exempt from the policy, and it implies that there will be others.

The FAQ lists Splatoon 2, Mario Kart 8 Deluxe, Arms and Super Smash Bros. Ultimate as games that definitely do require a membership.