With Nintendo launching its Switch Online service on 18 September, you’ll need that to play games online moving forward. That said, there are some exceptions and one of the most notable one is Fortnite.
Found on the Nintendo Switch Online FAQ page, it is stated that “Some games, such as Fortnite, can be played online without a Nintendo Switch membership.” That said, there is no indication as to what those other games might be.
That said, this isn’t completely unheard of. On Sony’s front, Free-to-play games like Fortnite and Warframe are exempt from the PlayStation Plus requirement. It may be the same for the Nintendo Switch, considering Fortnite’s exemption from the Switch Online requirement.
That said, this is speculation on our part, even if we’re not the only ones to come to this conclusion. Nintendo’s FAQ being so vague doesn’t help either. But for what it’s worth, games that need the Switch Online subscription will be marked when you see them in the Nintendo eShop or on Nintendo’s website.