It’s become commonplace for video game releases to come with a day-one patch, particularly for physical releases. Whether this is to add elements of the game that couldn’t fit on the disc or to fix bugs is usually up in the air. In the case of Super Smash Bros. Ultimate, it looks to be the latter.
The knowledge of this day-one update comes from game director Masahiro Sakurai himself in an interview with Famitsu. He states that this update will be critical for those who want any saved replays to work as intended. He never specifies anything beyond these replays, so it is unclear whether there is more to this update. It remains best to update before you play regardless.
“We will distribute our first update on launch day,” Sakurai said. “Players who purchased the digital version don’t need to worry, but players who purchased the physical version should apply this day-one patch before you play. This will also prevent your replays from going off track. By the way, if you save your replays as videos, you can keep them forever, but note that they take up a lot of space!”
Those going digital for Super Smash Bros. Ultimate should be fine, and everything should be readily working the moment you start playing. But physical consumers will need to run this update to ensure a fully working experience.
In regards to the update, no details have been revealed on how much space it will take up on your system at this time.