Being a game that was heavily speculated, in terms of newcomers, veterans, and features, Super Smash Bros. Ultimate was no stranger to fans making plenty of predictions. Many of which were expected by many fans to come true one way or another.
- Many people expected that the Inklings would be among the first, if not the first newcomer announced for the next iteration of Smash, due to the immense popularity of Splatoon. The Inklings were indeed the first confirmed characters for Ultimate, alongside series staples Mario and Link, although actual gameplay for the characters wasn't shown off until E3 2018.
- When Link's silhouette was shown in the Inkling teaser, many people assumed that the character had been updated to reflect The Legend of Zelda: Breath of the Wild, and if so, that he would also have his Tunic of the Wild as an alternate outfit in order to still represent the classic green outfit. Both things checked out come E3 2018.
- Since the Ice Climbers were cut from Super Smash Bros. for Nintendo 3DS and Wii U solely due to issues making their duality gimmick work on the 3DS, fans assumed that the fifth Smash game would bring them back by virtue of releasing on stronger hardware. Sure enough, when the E3 2018 presentation revealed them, nobody was surprised (but many were still excited).
- Many people were expecting Dark Samus to be an Echo Fighter for Samus, due to a suspicious absence of both her Assist Trophy and Samus' Dark Samus outfit. Chrom was also expected, due to Robin's Final Smash not being shown off in his/her character videonote . They were both confirmed on the 2018/8/8 Smash Direct, and Sakurai even teased those who made these predictions, saying "You may have seen this coming" immediately after revealing them.
- Fans had been expecting Simon Belmont as a newcomer as far back as Super Smash Bros. Brawl, both due to fellow Konami fighter Solid Snake appearing in that game and due to Simon's home series having appeared more often on Nintendo consoles than the latter's. Snake's return and fellow Konami character Bomberman's introduction as an Assist Trophy made the anticipation even greater. This all culminated in an incident on August 7, 2018 where the Galaga medley sample on the official Super Smash Bros. YouTube account accidentally got renamed "Bloody Tears/Monster Dance" before being changed back. Simon ended up getting his introduction trailer during the Smash Bros. Direct the next day.
- Fans were predicting that several characters who got DLC Mii Costumes in the previous game were ballot consolation prizesnote and that most of them would appear in the next game as playable. The Inklings were confirmed as the first newcomers in March 2018, Chrom and King K. Rool were confirmed in August, and Isabelle was confirmed in September. With Lloyd Irving being confirmed as a Mii costume in Kazuya's reveal, he was the last character that got put in as a Mii costume in the last game to stay as a Mii costume here.
- Sakurai has left multiple statements indicating that characters (including veterans like Snake and newcomers like Chrom and Dark Samus) are included by "popular demand". While some speculated that these were Smash Ballot choices, it wasn't until Sakurai released a column in Famitsu
after the August 2018 Nintendo Direct that he officially revealed that the Smash Ballot greatly influenced the roster for Ultimate. Before that, Nintendo had also promised that they would use the ballot for future Smash games. - Isabelle's absence as an Assist Trophy, popularity in the Ballot, and Mii costume in the previous game led to people correctly guessing that she would be a newcomer for the game. While most people thought she would be an Echo Fighter, at least one person accurately guessed she'd be a unique fighternote .
- The hidden mode from the August 2018 Direct being called "Spirits" and involving all or most of the characters getting killed was a foregone conclusion since Sakurai first teased at it, with many piecing it together from the blurred text and the trend of characters dying in the past few reveal trailers.
- Considering Ultimate's focus on Echo Fighters and the fact that Ken Masters is the original Shotoclone, it was taken for granted that he would be revealed as Ryu's Echo Fighter. Sakurai even references the above-mentioned fact that Ken is the original clone in fighting games.
- Many people guessed that Incineroar and Ken would share a reveal trailer due to both of them being fire-based physical fighters and Smash Bros. generally having a fire-based theme. And since both Ken and Incineroar are combat-based fighters, many also guessed that their reveal trailer would be set in the Boxing Ring.
- As The Game Awards 2018 were airing literally just hours before the game released, it was thought that Nintendo would unveil the first DLC character from the Fighters Pass at the event as a final surprise before the launch. Sure enough, "Challenger Pack 1" was unveiled during the event, with Joker being announced as well.
- After it was shown that Stage Builder was removed, there has been speculation about it being added back in an update. Nintendo leaked its return via a commercial posted on April 9, 2019.
- It was theorized that since Bayonetta came with her iconic handguns, Sakurai may have loosened up on the use of realistic firearms after Brawl. Sure enough, this was proven true once Joker was shown using his pistol.
- Many people expected female Inkling to represent Futaba’s Spirit due to their resemblance to each other.
- Due to the Dragon Quest series being the Trope Maker for the Eastern RPG, a personal favorite of Sakurai's, and having an updated version of Dragon Quest XI coming to the Switch in 2019, observers expected a Dragon Quest character to be added as DLC. They also correctly guessed that the Slime would be represented by Kirby in its Spirit Battle.
- Due to Nintendo and Microsoft having arranged a partnership with each other involving the Xbox Live Service and the porting of Microsoft-owned games like Minecraft to the Switch, there were theories that this would lead to a Microsoft-owned character showing up. Most assumed it would be Banjo and Kazooie due to that series' history with Nintendo. This came to pass when the two were revealed at E3 2019. Everyone knew that Spiral Mountain would be Banjo & Kazooie's home stage. People also predicted that they would use expendable items in their moveset (they get five Gold Feathers, used to perform Wonderwing, per stock), that the Mighty Jinjonator would be their Final Smash, and that Donkey Kong Country characters (fellow Rare creations) or Duck Hunt (a similar "mammal and bird" duo) would appear in their trailer.
- A 2019 video ad that showcased upcoming July Switch releases, and also featured a snippet of Hero's gameplay, was later hastily changed to say "Summer", which had most fans believing this accidentally tipped off a release within the month for Hero. They turned out to be correct once he was launched on the 30th.
- A dataminer had uncovered 16 dummy character slots among the files for World Of Light, with 6 of them seemingly being used by Piranha Plant and the Fighters Pass characters (although it was revealed that Hero and Banjo & Kazooie don't use up said slots). A select few believed that this meant there would be more DLC planned after the Fighters Pass, and this was confirmed to be the case after Terry was revealed.
- People have been using post-release Spirit Events as a measure for whether a title would get in as a DLC fighter. After all, logic dictates that if that character is a DLC, then its spirits wouldn't be featured as a standalone event. Indeed, many games for the Nintendo Switch have Spirit Events to commemorate their release. And yet surprisingly enough, Fire Emblem: Three Houses never got one. Sure enough, Byleth, the main protagonist of Three Houses, appears in Ultimate as the final character in the first Fighters Pass.
- Most fans expected the Fighters Pass format to continue in 2020 onward. This is indeed the case, as Fighters Pass 2 was announced within Byleth's showcase.
- There was the assumption that Fighters Pass 2 would be the final phase of DLC, despite Sakurai not explicitly saying so during the presentation for Byleth. He later confirmed it in a Famitsu column article in February 2020.
- Due to her massive popularity amongst both the staff and fans, as well as having won the ARMS Party Crash Bash over Ninjara, many fans have called Min Min being the ARMS fighter prior to her reveal.
- Several fans assumed that since Spirits are a replacement for trophies, this wouldn't prevent any of them from getting a character promotion like Mewtwo and Lucas in 4. Min Min becoming playable removed all doubt over this.
- For a good while, some fans argued the possibility that any character that already had a piece of art used for their spirit could simply use a different one, should they become playable. This was proven after Min Min's launch, as her fighter spirit makes use of a drawing that showcased her before ARMS launched.
- Alex was expected to arrive as an alt skin for Steve long before he was confirmed as playable.
- Kirby's Steve hat was theorized by some fans to just be Kirby, but in Minecraft's signature voxel style. The Steve presentation shows that this is indeed the case.
- Due to the relative notable absence of gaming/Smash news on Nintendo's part during November and early December 2020, some fans assumed that there would be a fighter reveal being prepared for that year's Game Awards, like with Joker two years prior. That came true, as the announcement for it was posted several hours before the event would start.
- The topic of specific noteworthy series coming with an oddly minimal amount of content in the base game was an extended debate, as that could have supposedly pointed to the arrival of more content from them such as fighters and spirits as DLC. This was eventually confirmed with Final Fantasy VII's Sephiroth coming via Fighters Pass 2, adding more content to bare bones material from that game. He was soon followed up by Xenoblade Chronicles 2's Pyra and Mythra, whose game had a relatively lacking amount of content compared to the first Xenoblade in the base game.
- Barret and Tifa were expected to receive Mii costumes, which they did with Sephiroth's arrival.
- For a good while, Fighters Pass 2 was seen by fans as an opportunity for Sakurai to finally add playable Xenoblade Chronicles 2 representation after missing out on the base roster, even if it wasn't Rex. In addition, at least one fan near-accurately theorized how Pyra & Mythra may operate as fighters in Smash.
- A few fans assumed that the Monster Hunter Mii costumes would return from the previous game, for the sake of promoting Monster Hunter: Rise. Ditto in regards to a spirit event.
- Technical issues displaying Rex and Pyra/Mythra at the same time as duo fighters (particularly the amount of detail that their designs would be required to render at once) was correctly theorized as the main determining factor behind the former being passed over and settling for the latter.
- Most people guessed that if Sora made it into the game, there’d be no explicit Disney references or imagery. They turned out to be mostly right, as with the exception of the Keyblade still bearing a Mickey Mouse keychain, no Disney world songs or spirits appear. In fact, the astute observers even realized that images of Donald Duck, Goofy, and King Mickey were removed from the pillars of Sora and Riku respectively when going into their Dive to the Heart segments.
