Duelist or Duelist Pro is an informal, fan-made game mode using a custom stage with no floor. The main objective of the game is to use a character's bomb recovery avoid the blast lines for as long as possible. Initially, characters often struggle to gain the height they need to avoid the bottom blast line, but as their damage increases, they must avoid being launched off the top. Some Duelist stages take place in an open box instead, where high knockback instead forces players into a tech situation to avoid being stage spiked.
Snake is the most popular character in Duelist; his C4 allows him to survive indefinitely, and his ability to act out of Cypher allows him to harass opponents with other moves. In particular, his forward aerial is a powerful spike, which is deadly because of the lack of solid ground in this format. Snake can also use his air dodges and grenades out of his up special to survive longer.
Duelist can also be played with other characters that have a bomb recovery. This includes Link, Young Link, Toon Link and Banjo & Kazooie. The latter of these shares many of the same traits as Snake, including the ability to act out of their up special, Shock Spring Jump. However, many of these characters do not have an infinite bomb recovery at 0%, and must rely on a handicap to participate. Peach can also play Duelist in theory, either through incredible luck or through mods, with her down special, which has a 1/240 () or 1/250 () chance of pulling a Bob-omb depending on the game. This no longer works in Ultimate, as she can no longer hurt herself with her own Bob-omb.