Yesterday, Nintendo released an update patch for Super Smash Bros. for Nintendo 3DS. The patch rebalances the game in a variety of ways, but Nintendo have not yet provided a list of patch notes detailing what the exact changes it makes are.
In lieu of proper patch notes, the community at Smashboards has taken it upon itself to figure out the finer changes made by the version 1.0.4 patch, and are documenting their findings in this forum thread. (Thanks, GoNintendo)
Detailed notes for each character affected by the patch can be found in the thread, and the documentation is constantly being updated as new information is released. If you’re a casual player, chances are you won’t understand a lot of the terminology being used. If you find yourself in the dark, this glossary should help.