I purchased the Animal Crossing New Leaf 3DS XL as my entrance into the system & its games.
I've recently procured a Zelda themed 3DS XL (Link Between Worlds bundle) and wanted to start playing on that one instead of the Animal Crossing one.
The game is pre-loaded on the machine and didn't come with a download code, cartridge, or e-shop code/receipt/whatever.
If I wanted to swap over to the newer 3DS I bought, would I just have to switch over the SD card or is there some special way to get my Animal Crossing to the new system? I was told there is a way but it'd wipe my Animal Crossing save – which is not an option I'm going to even consider.
Best Answer
What you need to do is a System Tranfer
And Nintendo says in their guide
Here you can watch a complete walkthrough on how to perform a system transfer.
Keep in mind that when you do a System Transfer, your Animal Crossing 3DS must be logged to your Nintendo Network ID and your Zelda 3DS must be without an account. If the Zelda 3DS comes with a pre-loaded game, log in with your NNID to link the game to your account, then format it and proceed with the system transfer.
Some things to have in mind while doing a system transfer are specified here
Here is a picture that shows in an illustrative what is transferred and what not
Source
So all your saved data will be transferred to your Zelda 3DS XL, but keep in mind that all of your data from the Animal Crossing 3DS XL will be erased but accesible from your Zelda 3DS XL (audios and photos are the only exception, so make a backup of those before transferring).