Nintendo has released the Super Smash Bros. Ultimate Version 10.1.0 Update, bringing a few changes and some new content.
For starters, the long-awaited FFVII villain Sephiroth can now be used after you purchase the DLC pack (if you didn't choose to complete the special in-game challenge before to unlock him early).
Other than this, players now can switch between "Random from all songs" and "Random from My Music" for the Battlefield, Small Battlefield, Big Battlefield and Final Destination stages. Also, some game-balance adjustments have been made and several issues have been fixed to improve the overall gameplay performance.
As to some other fighters, they have received a few tweaks as well, you can check the details here. As to the the full patch notes, checkhere.