100-Man Smash

100-Man Melee, 100-Man Brawl, 100-Man Smash, and Century Smash are Multi-Man modes in Super Smash Bros. Melee, Super Smash Bros. Brawl, Super Smash Bros. 4, and Super Smash Bros. Ultimate, respectively. They challenge the player to defeat one hundred opponents (Fighting Wire Frames in Melee, Fighting Alloys in Brawl, and Fighting Mii Team in SSB4 and Ultimate) without getting KO'd or Self-destructing. In all variations except 100-Man Melee, playable characters appear as every twenty-fifth opponent. Unlike the regular opponents, these characters are able to take advantage of any items that may appear. This mode usually takes a few minutes for players to defeat.

Items spawn periodically to help the player defeat the opponents. In Melee and Brawl, these items and their appearances are random; in SSB4 and Ultimate, the items appear on an extra moving platform and have a fixed sequence (in SSB4: Pow Block, Ray Gun, Smart Bomb, Pow Block, Killer Eye, Smart Bomb; in Ultimate: Pow Block, X Bomb, Fire Bar, Smart Bomb, Rage Blaster), but different intervals of appearance (SSB4 has the items brought into the screen every 30 seconds; the time interval is more randomized in Ultimate)

Checkpoints
A certain level of difficulty is programmed into four different checkpoints of 100-Man mode. After beating a certain amount of opponents, their behavior will change and they will gradually become more difficult. The rate at which the opponents are spawned will also increase. These checkpoints are shown by either a short pause in the spawning of opponents, or by a spike in the number spawned. The opponents' heightened knockback modifiers remain consistent at all stages of difficulty.

Beginning (0 opponents defeated)
At the beginning of the match, two to three opponents spawn and they will gradually increase to between four and five. However, they are at a very low level, that of a level 1 Computer Player. There will be a short pause after defeating the first 25.

25 opponents defeated
After 25 opponents are defeated, the amount at which they spawn will reset, but will gradually increase again. They are aggressive and slightly more dangerous than the first 25 foes.

50 opponents defeated
After 50 opponents are defeated, the amount at which they spawn will reach a maximum of between four and five. Most will constantly approach the player, while some may spread out among the stage. This checkpoint is where most players begin to encounter challenges. In Smash 4, the fiftieth foe will be in giant form.

90 opponents defeated
At some point after 90 opponents are defeated, there will be a small pause during the last few foes to acknowledge that the match is nearing its end. Nevertheless, the last few opponents will shield, dodge, and use smash attacks much more often.

99 opponents defeated
Right before the final challenger, there is one last pause. After the short pause following the defeat of 99 opponents, the final foe will spawn. It is much heavier than any of the previous foes, and as a result, is slightly harder to defeat. In Brawl, the last foe is the player's character (always player one if playing co-op). In Smash 4, the last foe will additionally be in giant form. In Ultimate, the last foe will instead be in normal size form.

In Super Smash Bros. Melee

 * Clearing 100-Man Melee will challenge the player to defeat, where victory will result in unlocking the character.
 * Clearing 100-Man Melee in under 4 minutes gives the Male Wire Frame trophy.

In Super Smash Bros. Brawl

 * Clearing 100-Man Brawl will challenge the player to defeat, where victory will result in unlocking the character.
 * Clearing 100-Man Brawl for the first time gives the Pitfall trophy.
 * Clearing 100-Man Brawl in under 3 minutes and 30 seconds gives the Ryuta Ippongi sticker.
 * Clearing 100-Man Brawl in under 4 minutes gives the Multi-Man Melee 1 (Melee) CD.
 * Clearing 100-Man Brawl with all characters gives the Blue Alloy trophy.

In

 * Clearing 100-Man Smash will challenge the player to defeat, where victory will result in unlocking the character and the WarioWare, Inc. stage.
 * Simply playing 100-Man Smash once will result in unlocking Victini to appear in Poké Balls and Master Balls.
 * Clearing 100-Man Smash for the first time gives the Auto-Healer Brawn Badge Equipment.
 * Clearing 100-Man Smash in under 3 minutes gives the custom move Effortless Blade for Marth.
 * Clearing 100-Man Smash with all characters gives the Shadow trophy.

In

 * Clearing 100-Man Smash will challenge the player to defeat, where victory will result in unlocking the character.
 * Clearing 100-Man Smash for the first time gives the Tetris: Type B CD.
 * Clearing 100-Man Smash in under 3 minutes gives the Wii Fit Plus Medley CD.
 * Clearing Solo 100-Man Smash as a in under 3 minutes gives the Multi-Man Melee 2 (Melee) CD.
 * Clearing Solo 100-Man Smash as in under 3 minutes gives the Speed Skater Shoes Equipment.

In Super Smash Bros. Ultimate

 * Clearing Century Smash alone under four minutes gives the Masked Lumen Spirit.
 * Clearing Century Smash alone as Ken using only special moves gives 3 Classic Tickets.
 * Clearing Century Smash alone on Great Plateau Tower within five minutes gives the Champion's Wig Mii headgear.
 * Clearing Century Smash alone as Wolf under five minutes gives 2500 Gold.

Trivia

 * In, if the player gets a Failure and presses "Quit", occasionally, during the last few frames of the transition from the mode to the menu, the option will change to the standard "Change Fighter" option.
 * Due to Ultimate having more unlockable characters than starter characters and its resultant streamlining of character unlock conditions, it is the first installment in the  series for which completing 100-Man Smash does not directly reward the player with an unlockable character.