Dave's Stupid Rule
Dave's Stupid Rule is a regulation that is in effect at most tournaments. While there are minor variations of the rule, they all have the same intention: to prevent a player from having an unfair advantage by playing the same stage multiple times in a set. Dave's Stupid Rule is reportedly named after Scamp, a player that was active in the early Melee metagame.
At the rule's simplest level, the player cannot pick the last stage they have won on during a set, while any stages of previous wins are fair game.
For example, in a Falco and Ike set, Ike wins on Battlefield and Lylat Cruise for two back-to-back matches, followed by Falco winning a match on Final Destination. The Ike player can select Battlefield, but they cannot select Lylat Cruise.
Dave's Stupid Rule, however, became controversial because of the "Mew2King Effect", wherein a player that wins on the counterpick stage of their opponent is able to pick his initial counterpick again. The effect was named after the smasher Mew2King who infamously kept using Marth on Final Destination against Fox and Falco after unlocking it by winning on their counterpick.
Some variations of Dave's Stupid Rule have appeared at multiple tournaments, often in order to provide better options for players or to fix perceived balance issues with the default ruling.
The most common variation of Dave's Stupid Rule is that a player cannot pick any stage they have won on during the set in question. Therefore, under this variation, the Falco player in the previous example would be free to pick Lylat Cruise for the next match, having previously lost on such a stage. Should the Falco player win, however, they can no longer pick the stage for future matches in the set, nor would the Ike player be allowed to choose Battlefield or Lylat Cruise, as they won on both stages.
Another variation to Dave's Stupid Rule states that if the counterpicking player chooses Random and ends up selecting a stage that was either previously played on or the player had previously won on, the match may continue unfettered. In some tournaments, where only three or four stages are allowed, this is often a viable strategy to get the same stage twice in one match.
One of the newer variations of Dave's Stupid Rule, known as "Modified DSR", states that no stage that has already been played in a set may be picked for another game in the same set, regardless of what the results of the previous game were. In the previous example with Falco and Ike, if Final Destination was the first stage selected and the Falco player lost, Modified DSR would not allow the Falco player to pick Final Destination, despite the stage's flat shape giving Falco the ability to pressure with his Blaster.
"Stage Dismissal Rule"
Amid the criticism of Dave's Stupid Rule and the creation of the "Mew2King effect", the German Smash community elected to modify Dave's Stupid Rule again to rectify the perceived flaws of the previous ruling. Jokingly called "Tero's Smart Rule" after tournament organiser Tero and later renamed the "Stage Dismissal Rule" (SDR) as a visual pun on DSR, the ruling states that players cannot pick a counterpick stage again if they have previously won on it. Initially obscure, the rule was given greater exposure after top professional smashers Scar and Armada praised it in a Melee It On Me podcast; it is now commonplace within the European Smash scene.
The Gentleman's Rule, sometimes called the Gentleman's Clause, is an addition to Dave's Stupid Rule used in some tournaments; according to the rule, any stage can be played on, provided all players consent to the stage's use. Assuming this is the case, Dave's Stupid Rule is ignored, potentially allowing for players to use counterpick stages that they have already used, as well as allowing for players to use stages that are generally banned in tournaments; the Gentleman's Rule can also be invoked to skip the process of stage striking. The rule is commonly invoked in cases of sandbagging, where higher-skilled players might allow their opponent to choose whatever stage they desire; Mew2King is particularly well-known for this in his sandbagging matches.
While the Gentleman's Rule is common at tournaments, tournament organisers still have the right to nullify it regardless of whether both players consent to a specific stage; this may be done as to preserve the integrity of the tournament, or for logistics reasons, such as by preventing a large stage like 75m from being picked.
"Bones' Stupid Rule"
In Bones' Ruleset, stage bans are temporary, chosen after character picks and are the only limited to stage selection. Bones's Stupid Rule states players need to change their temporary stage ban after every won match.