Switching from Gateway to CFW can be a pain, especially since all your saves were created on Gateway. There's only one way to get those saves to be usable on cia games, and that's to decrypt the saves and eventually import them in the end. It's a very tedious process, but worth it in the end to be able to keep all your saves you worked hard on for so long. Gateway has become more and more obsolete, with CFW being more convenient to work with. ESPECIALLY Arm9loaderhax!

This will guide you on how to convert Gateway saves, and import them into cia games. For those who want to abandon Gateway, or those who still want to keep Gateway but use CFW.
No other guide for this existed so I figured I had to create one.
Be sure you have PLENTY of time to work on this, you'll also need a ton of patience for this!

Thanks to @zhdarkstar for the tip about using JK Save Manager for just about everything! Made the guide ten times easier than it was before.



Requirements
JK Save Manager
CTRXplorer (Can also use FBI)




I. Preperation Steps

1. Right click and copy all your .sav files, paste them anywhere on your computer as backup

2. Make a new folder on your SD card, call it something like "Gateway saves"

3. Copy one of your .sav files into this folder

4. Look up that save file on 3DSDB to see what game it is

5. Rename that .sav file to
0004000002C23200

6. Make a new folder and name it to whatever game it is
Example:
SD:/Gateway saves/Super Mario 3D Land/


7. Place the 0004000002C23200 sav file in this new folder you just created

8. Repeat steps 3-7 until every game is setup this way. Can take a while to go through depending on how much saves you have, be really patient.

9. Download JK Save Manager.cia, and CTRXplorer.cia then place them anywhere on the SD card





II. Exporting & Importing the saves with JK Save Manager

1. Install all the cia games you need, for the games you're going to import saves with

2. Launch each and every game one time, allowing it to initialize which creates save data. Again, this takes a LOT of patience to go through

3. Install JK Save Manager and CTRXplorer cia's using any cia manager you like. Assemble them near the game cart icon on the home menu for quick access.

4. Open CTRXplorer and browse into the Gateway saves folder, then into one of the game folders

5. Copy the 0004000002C23200
sav file (Instructions on top screen, should be Y to copy), then press B twice until you're on the SD's root. Paste the file here using the Y button (Say yes to replace if the file already exists)

6. Press home and close it. Press select to open Gateway's rom menu and choose the game you're about to work on, but don't go into the game

7. Open JK Save Manager, go to "Cartridge", then choose "Export save". Name it anything such as a date ex: 5-8-16

8. Once you exported the save, go back to the main menu and choose "SD/Cia". Find the game and choose "Import save"

9. Repeat steps 4-8 until every game's save is exported then imported. You'll need extreme patience for this, as this is the only way to decrypt the .sav files.

10. Launch some of the games to confirm that the save did indeed transfer successfully.11. PLEASE make a backup of ALL the backed up saves from JK Save Manager, by uploading them to Google Drive or Dropbox!! This way your saves are forever safe!



About Card2 games
Certain games are card2 type games, where the save file is stored inside the cartridge. In our case, the save is stored inside the rom itself. Games like Pokemon XY/ORAS, Animal Crossing New Leaf, Tomodachi Life, Zelda Tri Force Heroes are card2 games. They don't produce a .sav file on the SD card like card1 games.
To export card2 saves, carry on by selecting the rom then using JK Save Manager to export the cartridge's save. Then import the save in SD/Cia.





Trivia
- Gateway saves are encrypted, so you can't export the save until you first renamed it to 0004000002C23200 and place it on the root. Since you can't have more than one of the same file name in one directory, you gotta work on these one by one. In this process, you're decrypting the saves.

- Some games like Fantasy Life and Theatrhythm Final Fantasy store their primary save data in "Extdata". If you plan on using the same NAND in the end, you don't have to worry about exporting/importing that.


- Saves from JK Save Manager, can be used by just about ANYBODY, from any region. They're highly universal and valuable to share on saves threads. Post them if you like to contribute!