Gold is a transformation that appears in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. Ultimate. Fighters affected by this transformation are referred to as gold fighters. It originates from the Mario universe.
Gold fighters deal more knockback to opponents from direct attacks and throws, but projectiles are unaffected. In 3DS only, the fighter will not flinch or receive knockback. The effect is accompanied by a damage output multiplier, indicated by a red particle effect around the affected fighter. Like Metal, the user become mute while the effect is active.
The Metal Killer spirit skill deals increased damage to gold fighters, treating them just like metal fighters. Conversely, Metal Slash does not treat gold fighters as metal fighters, dealing 1% damage instead of an Instant KO.
In Spirit battles
The effect originates from the Gold Flower power-up, introduced in New Super Mario Bros. 2, which allows Mario to transform into Gold Mario. Gold Mario is a variant of the Fire Mario transformation that allows Mario to shoot golden fireballs which turn breakable blocks and enemies into coins.