Can you go from the 3DS to the Wii?

yes you can, but it will add loads of wii game data onto the card which takes up a lot of space, don't put the 3ds card in while you're playing a game only insert the memory card when you're downloading something like a virtual consle games, as having a lot of wii data may muddle uo the 3ds's detection of the memory card.

Another thing if it doesn't work you need to slide the yellow bar on the card to the top this will unlock itfor use with wii.