Scheduled to launch anytime this month is the Nintendo Switch Online Service and just like the PlayStation Plus and Xbox Live Gold, it features a variety of services like online play, NES online, and much more which can be accessed by purchasing any of the plans currently offered by Nintendo. In the midst of the hype, Nintendo confirms in a statement issued to Game Informer that the Save Data Cloud Backup feature will not support some Nintendo Switch games (see statement below).
"The vast majority of Nintendo Switch games will support Save Data Cloud backup. However, in certain games, this feature would make it possible to, for example, regain items that had been traded to other players, or revert to a higher online multiplayer ranking that had been lost. To ensure fair play, Save Data Cloud backup may not be enabled for such games. To ensure that Save Data Cloud backups cannot be used to unfairly affect online multiplayer rankings, the feature will not be enabled in Splatoon 2."
Nintendo's comment was in response to the publication's article pointing out some titles which are not covered by the mentioned feature. Titles like Pokémon Let's Go Eevee & Pikachu and Splatoon 2 both of which were confirmed to not support the feature as mentioned in the fine print.
Aside from the Nintendo-published titles, Dark Souls Remastered, Dead Cells, FIFA 19, and NBA 2K19 were also mentioned to not support the feature despite the fact that all of these titles support the cloud save feature in PSN and Xbox Live. Nintendo Switch Online subscription will have two membership options (Individual, Family) made up of four price plans ($3.99= 1 month, $7.99-3 months, $19.99-12 months, $34.99 12 months/Family Membership).
Source: Game Informer