Super Smash Bros. Ultimate is one of the biggest games that Nintendo has ever made.
Even with all of the characters, stages, modes, and options available, the game size is pretty small in comparison to some other Triple-A games that sometimes require a day-one patch of over 50 GB.
Super Smash Bros. Ultimate’s download file size is just 13.6 GB for those buying a virtual version of the game on the Nintendo eShop.
In comparison, Super Smash Bros. for Wii U had a file size of 15.6 GB. It had less games, stages, and content overall, so it really goes to show how well Nintendo has been able to compress this massive game into one small file size.
You might want to look into getting a Micro SD card for Nintendo Switch, however, if you plan to get more games and even the DLC for Ultimate in the future, which will add onto the 13.6 GB initial download.