Nintendo Switch Online + Expansion Pack is the subscription tier that adds Nintendo 64 and Game Boy Advance games.
Nintendo launched the Expansion Pack tier on October 25, 2021. It includes the standard Nintendo Switch Online benefits, such as online play, cloud saves for supported games, and access to selected classic-game libraries, while adding Nintendo 64 and Sega Genesis titles. Nintendo later added Game Boy Advance games to the service in 2023.
The official name is longer than the commonly used shorthand “Expansion Pack.” It is not a separate console accessory or a downloadable game collection purchased permanently. Nintendo has also added other benefits to the tier, including selected downloadable content for certain Switch games. Availability of individual classic titles and downloadable content can vary by region and subscription status.