It seems like free-to-play games for Nintendo Switch might not require the Nintendo Switch Online service to use their online functionality.
A user on ResetEra has noted the fine-print on the eShop is missing on specific titles:
“To use online services you must have access to a wireless internet connection. Some online services may not be available in all countries. From the full launch of the Nintendo Switch Online membership service in 2018, online play requires a paid membership.”
The list of the titles missing this fine print include:
- Paladins
 - Fortnite
 - Pokémon Quest
 - Dawn of the Breakers
 - Fallout Shelter
 - Galak-Z: Variant S
 - Zaccaria Pinball
 - The Pinball Arcade
 - Kitten Squad
 - Pinball FX3
 
As with any rumor or unconfirmed information, take this with a grain of salt for now. We’ve reached out to Nintendo for clarification regarding this.
The Nintendo Switch Online paid service launches this September.
