Chests are an object found in Super Smash Bros. for Nintendo 3DS's Smash Run, and in Super Smash Bros. Ultimate's Adventure Mode: World of Light. In Smash Run, chests share their design and function with the Treasure Boxes seen in Kid Icarus: Uprising.
In Smash Run, chests can be found all over the map, and they can also be found behind doors when challenges are completed. Characters who approach a chest will make it open automatically, dispensing various contents; these contents will generally consist of stat-improving pickups, but trophies, custom parts, equipment, and items can also be dispensed from chests. Opening a chest will leave it open for the rest of the match; while its contents will not disappear in challenge rooms, they will disappear after a few seconds in the overworld's map.
The number of chests varies between matches, with some having more than others; certain events can also potentially cause more chests to spawn on the map, point out the location of chests that the player has missed, or increase the rewards dispensed by chests.
The uncommon enemy Mimicutie also disguises itself as a regular chest before it attacks players; approaching a Mimicutie disguised as a chest will prompt it to get up and attack players.
In World of Light, chests appear as an object on the overworld, and can contain things like coins, Spirit Points, and even Spirits. Their contents are never randomized, and are instead always the same on every playthrough. A Mimicutie Spirit Battle disguises itself as a chest in the Temple of Light area. Additionally, one chest in the Sacred Land area can be jumped into after opening it, which is required to awaken Chrom.