Ness

Ness is the main protagonist of the cult classic game EarthBound. He is an adventurous 13-year old boy who tries to stop an alien invasion in EarthBound. Ness is a playable fighter in every Super Smash Bros. game.

Super Smash Bros.
In Super Smash Bros., Ness is one of the unlockable fighters, and he can be unlocked by clearing 1P Game on a Normal difficulty setting with at least 3 stock and no Continues. Once the task has been fulfilled, the player's fighter has to fight Ness and defeat him, therefore unlocking him.

Ness was also a bit of a surprise addition to the roster, as no one expected such an obscure character to appear in the game.

Super Smash Bros. Melee
In Super Smash Bros. Melee, Ness is instead one of the starting fighters. He keeps all his special moves and gains a fourth move (PK Flash) like every other veteran.

When Melee was in development, Ness was intended to be excluded and replaced by Lucas from Mother 3, which was being developed for the Nintendo 64 at the time, but due to the cancellation of Mother 3's original release on the Nintendo 64, Ness was retrieved instead.

Super Smash Bros. Brawl
Ness returns as a veteran fighter in Brawl. This time around, he is accompanied by Lucas due to Mother 3's long-awaited release in April 2006. Ness is also an unlockable character, and he can be unlocked by playing The Subspace Emissary, reflecting 10 projectiles, or playing 5 VS Matches.

Super Smash Bros. for Nintendo 3DS / Wii U
Ness is brought back as a playable character in SSB4. He is an starter character on the Wii U version of the game, but he has to be unlocked on the Nintendo 3DS version. Ness can be unlocked on the Nintendo 3DS by playing 10 VS matches or beating Classic Mode.

Strangely, Ness was announced for SSB4, but Lucas was not. This led players to speculate that this was a similar case to Ness's appearance in Melee, where Lucas was planned to replace Ness. In Super Smash Bros. 4, however, there was no confirmation that Ness was going to be replaced by Lucas. It was simply just a matter of Sakurai choosing Ness over Lucas as the Mother representative. However, Lucas would be announced as a DLC fighter later on, proving players wrong.

Super Smash Bros. Ultimate
Ness returns with the rest of the entire roster in Ultimate, and he is an unlockable character. He was announced on June 12, 2018. As the first character in VS. Mode and Kirby's Classic Mode route, Ness can potentially be the first character unlocked in the game.

Trivia

 * Had Mother 3 not been delayed prior to Super Smash Bros. Melee's release, Ness would have been the only character from the first Super Smash Bros. to be removed from a later instalment.
 * Ness would have also been the first character to be replaced by another character. He would be followed by Young Link, who was replaced by Toon Link in Brawl.