Pokémon Heroes Unite is a new movie. It is a crossover with Pokémon, Ben 10, The Mixels and Transformers Robots in Disguise (2015).
When their worlds are in danger it's up to Ash Ketchum and Pikachu, Bumblebee, Ben Tennyson and the Mixels to stop the Syndicate of Evil and save their worlds.
One morning, when Ash Ketchum and Pikachu goes out of his house, he sees that Team Rocket has taken over the world of Pokémon and used multiple tank-like vaccums to suck all the town's civilians. He sees Fixit coming out through a portal and receives a message from Bumblebee. They follows Fixit through the portal to Iacon and meets Team Bee, Ben Tennyson, and the Mixels. Strongarm tells their interdimensional guests about his new invention, The Universe Portal Machine. As she says, it allows people to travel to other worlds. But Steeljaw has been spying on him, stole his idea and created his own Portal Machine. With it, he brought Team Rocket, King Nixel, and Vilgax to his dimension. They formed a Syndicate and proceed to steal energy from all the worlds. Since our heroes don't know where Steeljaw's lair is, they start with saving all of their worlds first.
They go to Mixopolis first and find King Nixel. King Nixel reveals that he uses the portal at Mixopolis to steal the mixing energy from the city. King Nixel has also captured the Mixing Class. Then, he sends the heroes to Mixopolis Stadium. The Cartoon Veterans survive in Mixopolis Stadium, and defeat the Nixel General. They break out of the stadium through a portal and end up in the city center. They see many Mixels possessed by the Nixels, but manage to push them out. The Cartoon Veterans go to the Mixopolis portal, which is a shortcut to King Nixel's castle. When they go in, Bumblebee realizes that there are generators that help King Nixel keep the portal open. They find the generators, and destroy them, shutting off the portal. When they find King Nixel, the Cartoon Veterans defeat him and save the Mixels without them noticing the Cartoon Veterans. They also find out that the Syndicate is building something.
Next, our heroes go to the World of Pokémon to fight Team Rocket. They meet Professor Oak, and follow him to Pallet Town. Professor Oak tells the Cartoon Veterans that they should find some guards which should help them find Team Rocket and the Pokémon Factory. Fortunately, they found the guards. Professor Oak then explains that Team Rocket uses the harvesters capture various Pokémon, and is extracting power from their elements in the factory. Team Rocket also captured Misty, Brock, Tracy, May, Max, Dawn, Piplup, Iris, Cilan, Clemont, Bonnie, Serena and Ash's classmates. Professor Oak told the Cartoon Veterans that they must go into the Pokémon Factory and free all the Pokémon. After Ben Tennyson asked if they have any secret agents (since he thought that it's like a spy movie), Professor Oak said that they have an agents in the Unova Region, who reveals to be Hoopa, but it's been captured by a Pokémon harvester. After destroying all the harvesters, the Cartoon Veterans go to the factory but during the journey, they find themselves in a hole and the Pichu brothers are going to make them their new crew for all eternity. Luckilly, the Pichu brothers frees them after they bring back their old crew. When the Cartoon Veterans arrived to the Rocket base, they free Hoopa, then freed all the Pokémon by opening the emergency vents. Later, they went up to the top of the Rocket base, they beat Team Rocket and rescue Ash's friends. The Cartoon Veterans find out that the villains are extracting energy for a Doomsday Device.
In Bellwood, the Cartoon Veterans see Vilgax has made the fortress made of alien tech. They also find a Alien energy of the Ultimatrix from Galvin Prime that is ending there, so they go in. After they re-activate the prisms, they get transported to Galvin Prime, where they meet Azmuth. Azmuth explains that Vilgax is extracting the super energy from the Ultimatrix to feed the Doomsday Machine. After freeing the aliens, they go to the inside of the Ultimatrix, where they defeat Vilgax. Flain figured out that every time they beat their enemies, they're running away, which was a part of a plan.
Finally, the Cartoon Veterans return to Cybertron, where Bumblebee finds Optimus Prime in his base and he also receives a message from Steeljaw that they've almost finished the Doomsday Machine and the Cartoon Veterans can't stop them. After Pikachu notices that Fixit has fleas, Sideswipe says that Fixit doesn't get the fleas. Then, Bumblebee figured out how Steeljaw could spy on him; he was using a flea-bot inside Fixit. So the Cartoon Veterans shrink themselves down and go to Fixit's body. They beat a lot of mini flea-bots throughout Fixit, and the Mixels, Ash Ketchum, Pikachu and Ben Tennyson gain Fixit's trust. They go to Fixit's head and beat the giant flea-bot. Blurr used the flea-bot's circuitry and locate Steeljaw's secret lair, which is situated under Kaon. When they get to Steeljaw's Doomsday lab, they find The Syndicate in a wheel-like machine which shields them. They beat the Syndicate but they see that the Doomsday Device is still counting down to destroy the universe and it can't be stopped. Luckilly, Pikachu unpluggs the Doomsday Machine and saves the universe.
After putting Steeljaw in jail, the Cartoon Veterans said themselves goodbye, but before they went, Bumblebee gave them the Cartoon Recallers in case of another event like this. Ash Ketchum said that Team Bee can visit him and Pikachu anytime they likes, but then he said they should get going, so they won't be charged by his mother for wasting her time, Ben Tennyson gave Bumblebee a copy of the Galvanic Mechamorph armour (since the real armor had Vilgax trapped inside, Ben Tennyson used the Autobots' Matter Duplicator to make a copy), then Flain and the Mixels thanked Team Bee for lending them their powers for holding King Nixel until the Mixels get back to Mixopolis. After this, Bumblebee says a familiar line: "Autobots, let's rev up and roll out!"
This film is based on NickToons Unite!