2008: On April Fools' Day in 2008, Cleod9 replaced the forums with "Forums baleeted" as a parody of the mass account hacking and porn spamming that took place weeks before. The word "Baleeted" also comes from of an internet series called Homestar Runner in a cartoon called 50 Emails.
2009: On April Fools' Day in 2009, Cleod9 announced that Nintendo had discovered Super Smash Flash 2 and had sent him a cease and desist order to shut down McLeodGaming and cancel the project. Cleod9 then put a link to what seemed to go to the Official Nintendo Forums, but actually went to the RickRoll'd video on YouTube. Cleod9 then announced that it was a an April Fools Joke and that SSF2 was still in development.
2010: Cleod9 did not make an April Fools' Day joke in 2010. However, the Smash Flash DOJO!!! did a sort of joke, redirecting people to an "OBJECTION!" page which said "You must be an April Fool if you didn't see this coming".
2011: Cleod9 did not make an April Fools' Day joke in 2011 either, though a DOJO!!! update was titled "Dojo Ending", and detailed the end of the Smash Flash DOJO!!!. However, if the reader scrolled down the page, there was a real update about "trigger items". These items appear to be normal items, but turn into shout-outs from Phoenix Wright when used (e.g. "OBJECTION!" "TAKE THAT!"), causing a variety of effects on the player.
2012: On April Fools' Day in 2012, Cleod9 redesigned the forums after allegedly demoting himself from the rank of site administrator. He even claimed that the red color that highlights the name of an administrator did not match his style. In turn, by "demoting" himself he also promoted all global moderators to site administrators and all regular users to global moderators, leaving only developers unchanged. During this day, a forum dedicated to spam was also opened. In reality, Cleod9 never demoted nor promoted anyone, including himself. He just changed the color of the usergroups. The spam forum was erased afterwards.
2013: On April Fools' Day in 2013, Cleod9 turned the main website upside down. For the forums, he replaced every profile picture with an image depicting Link's "Elegy of Emptiness" replica statue from The Legend of Zelda: Majora's Mask, based on the infamous creepypasta called the "Haunted Majora's Mask Cartridge Hoax" or "Ben Drowned". The site would also play the Lavender Town theme from Pokémon Red and Blue on an endless loop.
2014: On April Fools' Day in 2014, Cleod9 and the developers released a video on McLeodGaming's YouTube account which supposedly confirmed Mr. Incredible's inclusion as a playable character in SSF2. To make the joke look more authentic, Mr. Incredible was actually coded into into the game, with only one known visible attack, which was used as his down attack in the original Super Smash Flash. His sprites also hailed from the Game Boy Advance version of The Incredibles game but this time using Mr. Incredible's red attire. Additionally, Cleod9 announced a fake release date for demo v0.9b on August 21, 2014, which turned out to be the 8th anniversary of the release of SSF.
2015: On April Fools' Day in 2015, Cleod9 made an announcement saying he made some updates on the forums claiming that "the tone [of the forums] has always been a bit too casual, so these upgrades should make it much easier to converse in a more polite and respectable fashion.". In reality, Cleod9 added a tag under every profile pic calling every user a "loyal subject to his royalty cleod9[sic]" and added the text "ALL HAIL CLEOD9!" under very signature. Also, typing things on posts like "Cleod9" or "SSF2" would automatically result in calling them "royal ruler of the forums" or "greatest creation of his royalty cleod9[sic]", respectively. The smiley emoticon was also replaced with a mugshot of Cleod9 himself.
2016: Cleod9 did not make an April Fools' Day joke in 2016. However, the fifth SSF2 Dev Blog posted by developers that day, supposedly to be focused on costumes to be included in the game, was allegedly interrupted by a bot in the likeness of Cleod9, called ＣＬＥＯＤＢＯＴ, that has grown tired of working for the devs and has rebeled against them. As punishment for trying to seize him (and failing to do so), he executes his revenge by downloading his consciousness into the Sandbag. This joke invariably served as a confirmation for Sandbag's playable inclusion as the game's joke character, however, because it still seem it could be a joke not to be taken seriously, as fake character inclusions have been done in the past (such as Mr. Incredible's case), an extra Dev Blog was posted two days later to clarified the Sandbag was, indeed, made a playable character.
2017: Cleod9 did not make an April Fools' Day joke in 2017. Instead, developers published yet another video supposedly confirming new multiple playable newcomers for SSF2: the video features literal stages as the actual playable characters fighting each other. The match has Smashville facing against Final Destination on a Sandbag-esque stage, with the Falcon Flyer from Sand Ocean making an appearance at the end as well. As usual, developers achieve this joke thanks to model replacement with Smashville being a swap of Marth (using its floating platform as substitute for Marth's Falchion), Final Destination as a swap of Fox and the Falcon Flyer as swap of Captain Falcon.
2018: Cleod9 did not make an April Fools' Day joke in 2018. Instead, developers made an announcement that SSF2 would allegedly be completely rebranded as Flash Minus, named after the popular Super Smash Bros. Brawl mod Brawl Minus, due to the amount of ex-Brawl Minus developers that have joined their development team. This announcement came with a YouTube video introducing the new moveset of Sonic that parodies the style and format of Brawl Minus's own character introduction videos. The changes spotlighted in the video include the ability to cancel any attack where Sonic spins into a Homing Attack with no startup lag, the ability to hold Light Dash to indefinitely move forward with a guaranteed sweet spot, a forward aerial that could now always meteor smash opponents hit, down aerial and the Spring Jump spring being able to meteor smash, and an overall reduction of landing lag.
A second video was published the following hour, simply titled ".", which features a giant Sandbag in the background of Final Destination with a Master Hand on either side of the stage, acting as the hands of Sandbag. Sandbag's eyes and the crystals of Final Destination have an orange glow, and a slowed-down version of the songVs. Master Hand is played. For unknown reasons, the video was later deleted.
2010: On January 30, 2010, developer Steven Damian Borgers, backed up by several other Devs, spread a false rumor that Jigglypuff would be replaced with Gligar. This created an uproar amongst the members of the McLeodGaming Forums until the rumor was disproven on February 1 by the same developer.
On October 17, 2010, developer Geno posted a screenshot of Monkey D. Luffy using his Gum-Gum Munch-Munch (ゴムゴムのバク バク) against Ness, leading fans to assume that he would appear as an Assist Trophy in the upcoming Super Smash Flash 2 Demo 0.7. While it was later revealed to be a hoax, Luffy was eventually confirmed as a playable character at Super Smash Con 2016. It was later mentioned that the Luffy from the screenshot was actually an early version of him, before he was completely revamped for SSF2 Beta.
2011: On December 23, 2011, developer Faceless Max Void Silverman claimed to have uploaded the final character dev blog video for version 0.8, which was supposed to showcase Mega Man. However, after the usual intro, the video would just show Mega Man on Battlefield, using his side taunt repeatedly.
2013: On January, 2013, Damian once again spread the false rumor of Batman being a playable character, claiming he was added because of critically-acclaimed games like Batman: Arkham City getting released for the Wii U. Another former developer, RoyMaster4, also "confirmed" the rumor as well. People were more skeptical this time around, but some still fell for it.