You can copy screenshots to a microSD card.
Start System Settings and then select Data Management ⇒ Save Data/Screenshots ⇒ Manage Screenshots to copy screenshots between the system memory and the microSD card.
Software data cannot be moved from the console's system memory to the microSD card.
If you'd like to store software data on the microSD card, you must first delete the data from the console's system memory. Then, open Nintendo eShop and redownload the data to the microSD card.
Save data cannot be saved to a microSD card.