Screenshots and captured gameplay videos can be moved from the system memory to a microSD card, and vice versa. Downloadable software cannot. If you want to free up space on the system memory, simply delete or archive any saved software, and redownload it from the Nintendo eShop while a microSD card is inserted in the console.
When a microSD card is inserted in the console, it becomes the default save location for downloadable software.
Game save data cannot be copied to a microSD card.