It is a fan movie, which is created by Supereditor100.
The movie start with, Ryo Akiyama fighting the evil digimon Parallelmon, who has absorbs the villains of the legendary heroes who defeated them, and have them work for him, Ryo has the help from the Xros Heart United Army, but they weren't any match for Parallelmon's Digimon army. The group was finished, but Shoutmonand Gumdramon, weren't giving up and told Parallelmon, a voice said their willingness to never give up are motivating him, as a streak of fire appears in the sky, like a rocket, and a young man jumped from it and punches Apocalymon, Zenjirou was surprised by the fact someone punches a digimon, and deal damage to it.
The young man introduce himself as Marcus Damon and with him is is Digimon partner Agumon, Taiki recognized him as the one who helped him stop Quartzmon a few months ago, Agumon was still jealous the Marcus' Agumon can fly, a 14-year-old Tai appeared and says don't worry, and introduce himself to Xros Heart, Magnamon appeared, along with Davis who introduce himself to everyone, Takuya appeared along with Takato and his partner Guilmon, and Takato was so excited to be fighting with Tai and Davis. Tai think it was enough of an introduction and began by digivolving Agumon to WarGreymon, Marcus activated his D.N.A. charge and digivolve his Agumon to ShineGreymon, Takato biomerge with Guilmon to become Gallantmon, and Takuya did a Fusion Evolution to become Aldamon, the five heroes began to join in to help Ryo and Xros Heart to fight Parallelmon. Then the scene switches, explained that the battle was being viewed by a crystal ball that sees the future with a Parallelmon watching it all, and behind him a rally of Troopmons getting ready for a battle.
In the Tamers universe, Ryo was hanging in the roof of a building with his Cyberdramon|digimon partner]], then he was confronted by a mysterious man and his digimon, Ryo said hello to the man as he knew him, the Old Clock Shop Man asks Ryo for a favor to hunt a Digimon that has the power to travel through dimensions, and the Old Clock Shop Man needs Ryo, because he's already someone who can travel through different dimensions and asks for his help, otherwise the Digimon will destroy all the dimensions and everyone in it, Ryo looked back on the Digidestineds and the Tamers he made friends with, and agreed to help the Old Clock Shop Man.
Meanwhile, Parallelmon send out an army of Troopmons to each dimensions. In the Adventure 02 timeline, Tai and Davis are holding their own against the threat in the Digital World, with their friends being unable to go help them, WarGreymon and Magnamon will get tired out easily by this many digimons. In the Tamers timeline, Takato and Guilmon are being hunted down by a squadron of Troopmon, as the two biomerge to Gallantmon to escape. In the Frontier timeline, Takuya finally returned to the Digital World, only to be attacked by Troopmons, Takuya manages to get Bokomon, Neemon, Patamon, Salamon, and Lopmon from the Troopmon's grasp, he regained the ability to spirit evolve, and he spirit evolve into Aldamon, but they were too much for him to handle. In the Data squad timeline, Marcus and ShineGreymon charges and attack the Troopmons, but the sheer number of them were immense, and they were about to get tired soon.
Ryo was guided by the Old Clock Shop Man to the Xros wars timeline, a few months after the defeat of Quartzmon|Quartzmon]], the old man told Ryo to go find the members of Xros Heart and unite them to deal with Parallelmon. The old man decided to do something, while Ryo reunites Xros Heart.
Just as WarGreymon and Magnamon de-digivolves back into Agumon and Veemon, Tai and Davis were toast, then a dimensional rift opens under them, taking both them and their Digimon partners into it. When the two Digidestineds woke, they've come face to face with the Old Clock Shop Man in a castle tower, and he explained that a Digimon who has the power to travel to different dimensions is trying to conquer their dimension and others, the two didn't believe him at first, but the old man says he will bring three heroes from different dimensions here.
Gallantmon loses his energy and turned back into Takato and Guilmon, they were surrounded, but the old man came just in time, and dragged them to his dimension through the rift behind them. When Takato woke, he was greeted by Tai and Davis, who he was so excited to see and asks them to pinch him, if he's dreaming or not, Guilmon pinched him and Takato said "ow!", and this makes Takato very happy and was joyed for it to be real. Tai and Davis asks what's wrong with him, Takato explain that the two are TV show characters in his world, the two were shocked by the news, but calmed down to realizes they're famous in Takato's world, and happily sign autographs for Takato.
Takuya was knocked out, and returned to his human form, Bokomon and Neemon wake him up, and tells him it's not the time to be napping. Takuya, Bokomon, Neemon, and the three young Celestial Digimons, were surrounded. But the old man appeared and told them to follow him, the boy and the five Digimon didn't have much of a choice, and followed the man, and they followed him into a dimensional rift. Takuya look around to see, boys who have Digimon with them, and wonders where he is, the other wondered too. The old man appeared, and tells them to socialize with each other, Tai then asks where is he going, the man said that he needs to get the last hero in, and he's the most difficult to get.
Marcus and ShineGreymon fought hard against the Troopmon, but more keep coming, and ShineGreymon de-digivolves to Agumon. Marcus wasn't giving that easily and prepares to fight even more, even though he was too tired to fight, then the old man appeared and tell Marcus and Agumon to come with him, Marcus told the old man that he's not retreating from the battle, the old amn then tells Marcus, "why would the ultimate fighter waste energy with weak henchmen, the ultimate fighter should face stronger opponents", when Marcus heard those words, he agreed with the old man, and the old man tells him that he'll face even stronger opponents, if Marcus would just follow him, Marcus agrees and tells Agumon to follow the old man, and he lead them into a dimensional rift. Marcus and Agumon arrives, to see other humans in here as well, some of them have Digimon partners as well. Tai was surprised to see that the last hero has an Agumon as a partner as well.
The old man asks the five heroes and their digimons to greet each other. Tai introduce himself first, as the leaders of the Digidestineds and bearer of the Crest of Courage, he's an ace soccer player in his middle school, his Digimon partner is Agumon. Davis introduced himself next, as the leader of the younger Digidestineds and highly respect Tai, his Digimon partner is Veemon. Takato introduced himself, as a tamer who loves everything about Digimon, his Digimon is Guilmon. Takuya introduced himself as the Legendary Warrior of Fire, who wields the power of AncientGreymon. Marcus was the one who introduced himself, he told them he was an agent for DATS, an organization that deals with Digimon crimes, and keep it a secret to the public, his Digimon partner is also an Agumon.
Menwhile, Ryo confront Taiki in his house, saying he needs his help in fighting Parallelmon. Taiki agreed saying he won't turn his back on anyone, Ryo asks him to contact the rest of Xros Heart, as he needs all their help, Taiki agreed and contacted Akari, Zenjirou, Kiriha, Nene, Yuu, and Tagiru. Tagiru, Akari, Zenjirou, and Yuu arrives and met with Ryo and Taiki, Ryo explained he is a hero from another dimension and the old clock shop man sent him to help stop Parallelmon, and told him of his power, Taiki was even determine because if he don't do this, other dimensions will be destroyed and it will be like D5. Parallelmon arrived in the human world, and using Quartzmon's power, he turned everything into DigiQuartz, Xros Heart was unaffected by it, and they prepared themselves for battle.
Meanwhile, the five heroes dashed to where Parallelmon is, but were confronted by Tactimon. Marcus charges at Tactimon, and punches him, getting Tactimon to move a few steps back, the four boys were surprised by Marcus being able to counteract a digimon. Tactimon was surprised that a human was able to best him, and says it was impossible, Marcus says it's not impossible because he has potential in him to do it, and activates his D.N.A. to digivolve Agumon to ShineGreymon, Tactimon charges and counterattacks with ShineGreymon. Tai decided to help by digivolving Agumon to WarGreymon and orders him to help ShineGreymon, Marcus didn't like it and tells Tai he didn't needed his help, tai thinks Marcus was pig-headed and stubborn and decides to help anyway. Things turn to the worst when Dorbickmon, NeoVamdemon, Zamielmon, Splashmon, and Gravimon came and DigiXros to GrandGeneramon, Takato quickly biomerge to Gallantmon and Takuya quickly fusion evolves to Aldamon, Davis was quickly surprised by the two unique evolution, and tells Tai why isn't he shocked, Tai told him after seeing Marcus fight a digimon with his bare hands and survive, he'll believe anything.
Ryo and Xros Heart fought valiantly, but Parallelmon played dirty by resurrecting the Dark Masters to lead his army, Xros Heart DigiXros Shoutmon X4K, while Tagiru and Yuu digivolves Gumdramon to Arresterdramon and Damemon to Tuwarmon.