Due to the unprotected nature of most Wii saves, Dolphin has functionality built in to export and import Wii save files.

To export from Dolphin, right click the game, select “Export Wii Save”, and select the root of your SD card. Then go into your save settings, find the file on your SD card, and copy it over to the Wii system memory.

To import saves, copy them to the SD card, then in Dolphin go to the Tools menu, and within there are “Import Wii Save” (singular) and “Import Wii Saves” (multiple) that you can then provide the location of a single file or whole SD card to import your saves.

The only exceptions to this process are games that use protected Wii saves that cannot be copied from the system menu. In that case, you need to use a modded console and a save manager of your choice (like SaveGame Manager GX), but the process is broadly the same.