The undub is possible but no many people want it, we can only decompress the English voices of the US version. But one day we will get the othe voices and get our precious undub!!An undub for Smash isn't possible, due to how it was made. However, you can use NTRboot to play it in Japanese which is the closest you can get an undub for smash for, for the 3ds version. Of course the game need to be the JPN version.