When starting Super Smash Bros. Ultimate, players initially have access to 8 fighters.
Those eight are the original roster from the first Super Smash Bros. on Nintendo 64: Mario, Donkey Kong, Link, Samus, Yoshi, Kirby, Fox, and Pikachu. The deliberately small starting lineup gives Ultimate a direct connection to the series’ origins, even though the finished game contains a much larger crossover cast.
Most of Ultimate’s other fighters begin locked. Players can unlock them through several routes, including completing Classic Mode, progressing through World of Light, or repeatedly playing battles that trigger challenger encounters. The unlockable system makes the starting roster expand gradually rather than presenting the entire cast immediately.
The number 8 refers to the fighters available at the beginning, not Ultimate’s eventual roster. The base game launched with 74 playable fighters, and downloadable content later increased the total substantially. The game also supports battles with up to eight players, but that is a separate use of the number.