Topic: Question re 3DS saves / transfer process

I've hardly touched my 3DS in the last year or so (awful of me I know), and I don't see that changing much any time in the immediate future - as such, I am planning on trading it in at CEX.

However, if at all possible, I would rather not lose the many hours I have put in to certain games. More specifically, I really don't want to lose my Pokemon progress as I figure at some point further down the line when a new one releases I will probably pick up a 3DS on the cheap and will want to be able to transfer in all of my Pokemon.

First question - is save data tied to the SD card or the game cart? Both Pokemon games I own are physical copies. If the save data is tied to the cartridge, is this also tied to a specific system (ie would I still need to do a full system transfer to the new system before I could use my old saves)?

If not, brilliant (I'll just transfer all my 'mon to OR, hold on to that and trade in everything else)! If save data IS system locked, then I have a question re the system transfer process. Could I start the "System Transfer via PC" process with the system I want to sell, and take it up to the point where everything is copied to the PC, and then just leave that there indefinitely until I want to load it into a new system further down the line? Or do the old and new 3DS consoles specifically need to interface with each other at some point in the process?

Haven't been able to find anything conclusive online, so any help / insight anyone could offer would be very much appreciated!

All the facts in regards to cross-system stuff:

• Save data is encrypted with a key unique to the system (in the case of Digital games) or the cartridge (in the case of Physical games)
• Downloaded digital games are encrypted with a key unique to the system.
• Nintendo has released an application which allows the one-way transfer of save data from a cartridge to a system's digital version of the same game.
• Hardware, Cartridges and Amiibos included, and their associated save data, are in no way tied to the consoles they are played on.
• Cartridges are region locked, but no other hardware or accessories are.
• Your digital game purchases and themes are tied to your NNID, (Nintendo Network ID)
• Your NNID can only be attached to a single system at any one time.
• Your NNID is region-locked.
• A system transfer can be performed that will transfer your NNID from one system to another. Both systems must be present and updated for the duration of the transfer. Optionally, during this process, the save data from digital games will be unencrypted, transferred across to the new system, and then re-encrypted for that system. Optionally, during this process, all installed digital games can be unencrypted, be transferred (either wirelessly, or via the physical transfer of the SD card) across to the new system so that they do not have to be redownloaded from the eShop, and then re-encrypted for that system. The system which the NNID was transferred off will subsequently format itself.
• If the old system is not available, or has been formatted, then Nintendo can be contacted to manually disconnect the NNID from that system and attach it to the new one. Verification in the form of the old system's serial number, and a few of the purchases made on its NNID, will be required. As digital game's save data is stored and encrypted on that system, it cannot be transferred to the new system. (Homebrew methods exist however that allow the unencrypting of saves, which can then be backed up to a computer, and restored to any system regardless) Digital games will also need to be redownloaded, even if they are on the SD card, as they are also encrypted on a per-system basis.
• A system which has had its NNID manually removed by Nintendo will have its digital game liscences revoked upon the next time it connects to the internet. This will render the installed digital games unplayable.