It is a regular afternoon in the World of Sports, which is a flat planet shaped like the Super Smash Bros. symbol. Everyone is in attendance at the Central Stadium, an open air arena reminiscent of Midair Stadium located in the center of the world. The announcer is commenting over a dramatic battle between Donkey Kong, Samus, Luigi, and Link. In the stands, everyone's supporting cast (that Nintendo can get the rights to show up) is watching the battle with held breath, cleanly divided by series. Its down to the final fifteen seconds. Donkey Kong buries Luigi with Headbutt, but before he gets the chance to attack again Samus's Charge Shot hits Donkey Kong and almost KOs him. Spinning Kong lets DK make it back to the ledge. Link moves in on Samus, and while she tries to stop him by firing off a Super Missile, the Hylian Shield tanks it and lets Link finishes her off with a dash attack. Luigi climbs out of the hole he's in. Donkey Kong climbs up the ledge, but Link's down smash attack takes care of him. Luigi runs up to Link, who responds with a Spin Attack, but Luigi does a backward roll just in time. With Link caught in the endlag, Luigi short hops next to Link and delivers a Fire Jump Punch! Link is sent clean out of the ring for a KO. Everyone respawns, raring for more action, but TIME is called, and Luigi is the victor!.Meanwhile, a mysterious thick smoke begins to surround the stadium. Something within the smoke steals away all of the vehicles and other transportation parked outside: the Blue Falcon, Great Fox, Halberd, Epona, Odyssey... and so on. All vanished by a force who knows how big.
Luigi shakes hands with the other fighters, who then ride platforms off the stage, then the announcer calls for new challengers. Cutscene stops for character select, which is a menu. When it returns, the game is set to what appears to be a Time battle between two random Fighters, Luigi, and the player's character. This is a lie. A minute into the match, the smoke fills the stadium and a giant smoky dragon appears! The game shifts from Time to "Team Unwinnable Boss Battle" with the fighters all being one team and the dragon "Manudractory" being the boss. "Manudractory" can never lose their last point of health. The player inevitably loses and the battle ends.
"Manudractory" looks over the assembled fighters and the audience with distain, then they form a massive upwelling of energy below the arena and blow everyone all across the World of Sports. The force is so great that the ground below the stadium is split into four pieces, with the fault lines running all the way to the edges of the flat world. The world itself is sundered into four pieces, and each portion of Central Stadium sloughs off into the middle where they vanish into a field of smoke.
The player's selected fighter wakes up in the largest corner of the world, the upper right corner, due to the announcer shouting their name. It actually plays at a lower volume the first three time, only rising to full volume for the shout that succeeds. The announcer coughs and says that they think that the player's fighter is the last of the fighters he had to find. They feel sick and weak somehow, and they think "Manudractory" is looking to replace the announcer as one of the driving forces of this world. As such, its up to the fighters to stop "Manudractory" and save the world! But first, they have to fix the world, and to do that, they'll need figure out how to get around the shattered world.
This is when Slippy Toad shows up. It seems no one has a way to get around the World of Sports; Slippy ran the numbers and it seems that everyone's ships and other forms of transportation are missing! He has an idea: he thinks he could build a ship if he had the parts, but there are these strange "Copy Fighters" running about. These blatantly artifical and personality-less robotic doubles of all the fighters are getting in everyone's way, so even though Slippy knows where the key items he needs are he is unable to reach them himself. The announcer is confident that the fighters can defeat the copies and retrieve the parts Thus, Quest 1 is to travel to four different locations on this corner of the world to find the parts and bring them to Slippy. In the meantime, the remaining fighters set camp. Oddly enough, even though Copy Fighters break down into pieces when defeated, there are always more of the things.
Along the way, the fighters encounter some of their friends. Chatot (Ideally from Pokémon Mystery Dungeon Explorers games, but maybe helps to keep the camp organized, shuffling around the fighters and NPCs available to talk to ot calling out someone specific. Linhardt von Hevring analyzes any of the strange "Artifacts" the fighters obtain, finding that each of them can be used as a potent power-up. The Cosmic Spirit appears if the player is unable to beat one of the levels as the level skip function. Plus, Slippy Toad builds a payphone for the fighters so that they can call the announcer any time, since the announcer finds it hard to notice the fighters when there isn't an intense battle happening.
With the parts aqcuired, Slippy can complete the Arena Wing, a combination stage, ship, and living quarters set for a map trotting adventure. The Cosmic Spirit declares herself the navigator, introducing herself if the player has not yet met her prior to this point. Meanwhile, Pearl, Marina, and Redd sneak aboard as stowaways, looking for a ride for business reasons. But in the meantime, they also have services to offer: Pearl & Marina can set the Arena Wing's music and Redd sells artwork that can be displayed in the Arena Wing.
The player can now proceed to the worlds of the upper left corner, in which they can find the items needed to join the upper left corner to the upper right corner. Then they can enter the worlds of the lower right corner in which they can find the items needed to join the lower right corner to the top half of the World of Sports. As they do this, the player encounters NPCs who are not a part of the Arena Wing's crew but could still use some help with things.
Before they can proceed to the lower left corner, Manudractory attacks the Arena Wing directly in a boss battle set directly on the Arena Wing. It draws similarities to Mecha Ridley's battle in The Subspace Emmissary. Once that's over with, the player can access the worlds of the lower right corner, including a fake out ending where they beat Manudractory for a "final" time. Manudractory retreats, and the characters use the items collected to join the lower left corner to the rest of the World of Sports. The smoke clears and the announcer is back to full strength. But even with that, the beloved Central Stadium is still gone. It is a centerpiece of the community, and while there may not be a hole in the world anymore the absence of the stadium leaves a hole in everyone's heart. Everyone, even the stowaways who were just here for busniess reasons, resolve to go and get it back.
The Arena Wing flies to the very edge of the world and flips around it, revealing an seedy underbelly on the reverse side of the World of Sports. It turns out Manudractory's vile processing plant has been the true source of the Copy Fighters, and they've been using them to run their own never ending battling ring in the Central Stadium. In their ideal world, there's no space for laughter, or crying, or respect, or love. Only conflict and testing and numbers and powerscaling. When a Copy Fighter is defeated and breaks, they don't get repaired or even honored. Those parts are discarded as litter and the processing plant just makes more Copy Fighters. Everyone is deeply distraught, and there's only one thing to do: shut the whole operation down at the source and banish Manudractory. First, the fighters battle to reclaim the Central Stadium, an world which deliberately has a very minimal world map. Then they proceed to the processing plant for the big finale.
The processing plant is a world like any other world, but to really sell the moment its the only world with an exterior (its empty) and an interior. The penultimate level has some set up: It uses a unique stage representing Manudractory's furnace, but its too hot for the fighters to survive so just to enter the level the player's fighter needs to use a special "Rune Box" created through a combination of the announcer's, Slippy Toad's, and Linhardt von Hevring's skills. The Rune Box grants a special variant of Slow Super Armor, Rune Fighters are unable to jump at all, forcing the player to complete one last puzzle on the world map involving moving platform manipulation just to reach the level. The level's final battle is a boss encounter against the furnace. Following the furnace's defeat the fighters take the fight to Manudractory one final time. Winning weakens Manudractory greatly, but they attempt to run away. This leads into a final cutscene where Slippy Toad sets the Arena Wing's propellers to full blast to blow Manudractory into non-existence. They fight back with a massive smoky blast, which intially pushes the Arena Wing back so far it ends up back on the front side of the World of Sports. But the announcer rallies the love and support of all the real characters all around the world that the player has been helping across the entirety of Adventure Mode, and the love and support of all of the fighters. With that and a battle cry from the announcer, the Arena Wing overpowers Manudractory. (Think Kirby game finales, and you're on the right track. If you don't have a frame of reference, think QTE button mashing with something wibble wobbling between actually cool and extreemly saccharine.)
Roll credits. Static images show the Arena Wing carrying the Central Stadium back from the reverse side of the World of Sports to the front side, and many more implied character interactions between characters and fighters of different series. When the credits end, one final cutscene plays showing another Time Battle at Central Stadium, this time with the stands having the characters of different series mixed together. The crew of the Arena Wing sit together in a special section of the stadium. Where the opening cutscene used four fighters from the original 12 in the battle, this one would instead involve four of fighters new to this game. Following said cutscene, there is a final picture of all the fighters and the crew of the Arena Wing standing in front of the ship.
If the game is started after credits roll, all the NPCs are oddly still operating/stowing away on the Arena Wing. Talking to any of them has dialouge options for what's happening. The announcer wants to keep the Arena Wing ready, with the non-announcer NPCs conjecturing that it is because they like the crew too much to let them go even though the World of Sports is safe. The announcer denies this, saying they just want to be prepared. The stowaways are still on board because they like the crew and they were delcared honorary members of it. Now they're just hanging out. Central Stadium is an accessible location from each of the four quadrants of the front side of the World of Sports, home to an All Star Mode spin off where you can use Artifiacts and the game's boss rush, the levels used for the area's evil counterpart, and replaying the mode's opening scenario. It also serves as the ground bound link to each of the four quadrants of the World of Sports for realism reasons. A door in Manudractory's processing plant appears for replaying Manudractory's boss fight on the Arena Wing.
