How do Pokemon cartridges work in relation to SD cards on the 3ds?

So, I am a little confused with this topic.

If you try to play a Pokemon game on a 3ds without an SD card in your ds then it will not let you play. That makes you think that you can’t save the game unless you have an SD card in, right? And then that makes you think that all the save data will be saved onto the SD card, right?

But if you put a cartridge that has played the game into a different 3ds with a different SD card, then it will put you where you left off. So what is saved to the SD card?

Sorry if this question is not allowed.

Pleaselog inorregisterto add a comment.

On the 3DS, the game’s save file is directly stored in the cartridge. However, any extra data, such as photos from the Alola Photo Club, are saved to the SD card. This is the reason. Why they couldn’t just let you play without the SD and just disable the ALPC, idk, that’s GameFreak. The sources I used are down below.

The Alola Photo Club has been introduced, which allows players to take photos with the Pokémon in their party. These photos can then be edited with stickers, posted to the Pokémon Global Link, or saved to the 3DS’s SD card. The player also has the option of doing an impromptu photoshoot after a Pokémon in their…