At Slateport City, Hoenn, Genesect opens the mailbox near his house and receives an invitation from someone. Genesect reads, "Dear Genesect, you are formally invited to celebrate the Star Festival in the Sinnoh region, which is at Jubilife City. Sincerely, Dawn."
The invitation was sent from Dawn, the Super Contest Hall Princess. Every 100 years, a special comet passes through the skies of the Sinnoh region. Genesect folds into his High-Speed Flight Form as he flies to Jubilife City at the Sinnoh region.
At Jubilife City, the citizens of the city are celebrating the Star Festival as Star Bits rain down in the city. The Jubilife City Star Festival is a celestial light show. Genesect lands onto the ground as he unfolds. Then, he meets Jirachi and Mewtwo. "Greetings, Mewtwo and Jirachi," greeted Genesect. "How are you doing?"
"I'm doing great!" replied Jirachi enthusiastically. "I am celebrating the Star Festival, and it happens every 100 years in the Sinnoh region. Interestingly, it reminds me of the Millennium Comet celebration in the Hoenn region, but it is completely different. Anyways, Genesect, how are you doing?"
"I'm doing just fine, Jirachi. Oh, and Mewtwo, when I was alone in space after we defeated the U.I.M.S. Delta, something wacky just happened. I battled against Star Dream, which was piloted by Sonny the Bird."
"What? I don't believe that!" replied Mewtwo in confusion, which is not a status condition. "I'm not buying on what Genesect just told me."
"I disagree with you, Mewtwo," added Jirachi, as he pulls out evidence of Genesect's belief, which is the scrap metal of Star Dream Soul OS and the orange feathers of Sonny the Bird. "I just saw the debris of Star Dream Soul OS at the Hoenn region. Therefore, it did happen."
"Let's just enjoy the Star Festival, and not talk about weird and random nonsense stories, which turned out to be real," reassured Genesect firmly.
Interestingly, Genesect becomes familiar with the "Super Mario Galaxy" references. "Wait a second, doesn't that seem familiar to you, guys?" questioned Genesect suspiciously. "The Star Festival is a 'Super Mario Galaxy' reference, and that special comet is the Comet Observatory. In fact, this story is a crossover of 'Genesect In Space' and 'Super Mario Galaxy'."
Jirachi, Genesect, and Mewtwo collect the Star Bits while enjoying the Star Festival. Upon tasting it, it is a honey-flavored treat, much to their satisfaction. "The Star Bits are so delicious," praised Jirachi, as he eats the Star Bits.
Suddenly, the ground begins to shake like an earthquake; after it stops, a dimensional rift begins to appear. "What's going on?!" exclaimed Jirachi in shock.
"I know what's going on," said Genesect, "I see an Ultra Wormhole is about to open. That means an alien invasion is about to begin."
Abruptly, an Ultra Wormhole is opened that a massive race of aliens that are divided into five groups of aliens emerge from an Ultra Wormhole. The Invasion of All Aliens Squad, known as the I.A.A.S., arrives at Jubilife City. These malicious menacing mean aliens are attacking Jubilife City. "I knew I was right all along," said Genesect. "It's because I have seen this before, but the enemies attacking Jubilife City are different than the ones I have seen in the game, which was Bowser and his armada of Airship Fortresses attacking the Mushroom Kingdom."
"Everyone is here!" exclaimed Jirachi in surprising horror.
"Yeah, Jirachi, the U.I.M.S. Delta merged with the U.I.M.S. Original that they became the U.I.M.S. Omega, a subgroup of the Invasion of All Aliens Squad. I do remember the I.A.S., the Infected Alien Squad, from my first space adventure. Now, the Infected Alien Squad Deluxe, known as the I.A.S. DX, are the spiritual successors, another subgroup of the I.A.A.S. race."
The Infected Alien Squad Deluxe has the color schemes of white, red, golden-yellow, and green. Multiple Infected Tentacool DX are on their mini UFOs while the Infected Hexacool DX is on his medium-sized UFO. Additionally, the Infected Tentacruel King Overlord DX is on his UFO.
They are attacking the city by shooting their photon laser guns from their UFOs. "The colors of the I.A.S. DX reminds me of Zero Two from 'Kirby 64: The Crystal Shards' for the Nintendo 64," commented Jirachi.
"The Infected Bug Pokemon reminds me of 'Galaga'," added Mewtwo.
Jirachi then becomes horrified as he sees the Ultra Infected Vespiquen and her army of Infected Bug Pokemon. The Infected Bug Pokemon, including the Ultra Infected Vespiquen, have the color scheme of Deoxys, much like the classic Infected Alien Squad.
Along with that, the brainwashed Ultra Beasts and UB Fighters are in her command. "Oh my god she's huge!" screamed Jirachi in horror, as the Ultra Infected Vespiquen's appearance is intimidating.
The Ultra Infected Vespiquen is the Infected Vespiquen's mutated form after consuming a Power Star, which is the reason why the purple gem on her head is glowing golden-yellow and why she is insanely large as Eternatus' Eternamax form. Also, she is currently fused with Nihilego. The neurotoxins of Nihilego, the auras of the Beast Boost (Necrozma's Light), and the consumed Power Star all together is the result of the upgrade to the simple recolor of the Infected Vespiquen. Infected Vespiquen's mutated form resembles that of the unnamed Galaga Queen from "Galaga 3D Impact", the final boss of the game in "Pac-Man and Galaga Dimensions" for the Nintendo 3DS. The head of the mutated Infected Vespiquen has two pairs of large and long antennae and the third pair of antennae are small and short. On her head, she has a pair of orange-colored scythes of a mantis. Additionally, she has another pair of limbs on her upper body, and the hands resemble leaves. Behind her long slender upper body of the gargantuan queen, she has a wheel of seven peacock-like bee wings, based on the royal cloak's regal collar. Between her lower body and the upper body, it has a beehive-like nest where the Infected Bug Pokemon are created along with the lower body's second beehive-like nest. Behind the lower body, she also has five bee wings that resemble the cape of the royal cloak. All the bee wings have a purple eye on each tip of the wing. Lastly, she has a tail protruding from the lower body's hive, and it has a pair of purple mandibles at the end of the tail. The Ultra Infected Vespiquen has a pair of white horns attached to the bell of the fused Nihilego.
Luckily, the Light Trio and the Cosmog Line are unaffected by the commands of the new evil leader. A swarm of Infected Beedrill, Infected Butterfree, Infected Ledian Bosses, and Infected Combee attack by shooting out cyan photon laser guns. On the other hand, multiple Nihilego, Buzzwole, Pheromosa, Xurkitree, Celesteela, Kartana, Guzzlord, Poipole, Naganadel, Stakataka, and Blacephalon attack by using their strong moves while multiple UB Fighters Paperplane in all three types, UB Fighter Saucers, UB Fighter Shapeshifters, UB Fighter Boomerangs, and UB Fighter Bolts attack by shooting their signature weapons.
"I didn't know there are multiple Celesteela, Guzzlord, and Stakataka!" realized Jirachi in astonishment.
"Well, here we go again," commented Genesect. "Looks like we'll have to rescue the Ultra Beasts from being brainwashed again. But this time, the Ultra Infected Vespiquen is the new evil leader. Interestingly, she is the queen of two subgroups of the I.A.A.S., the Infected Bug Pokemon and the Ultra Beasts."
"And the fifth and last subgroup of the I.A.A.S. is none other than the Dark Matter race," concluded Mewtwo.
"Wait, what? You don't see that every day!" cried Genesect, as he was mind blown by this.
The Dark Matter clan raids the city as the army of N-Zs use their spears, parasols, boomerangs, and archers. Some of N-Zs have a Waddle Doo counterpart, known as N-Y, use their beam whip attacks. Multiple Dark Matter Spiders, including their three elemental counterparts, attack the city. A horde of mini Dark Matter attack by shooting out black and purple laser projectiles from their cycloptic eye. The leader of the Dark Matter clan, Dark Matter Swordsman, uses his sword to slice the buildings. Dark Matter Hornets and Dark Matter Dragonflies are also assisting the spiders too.
The U.I.M.S. Omega battleships, the Hammerhead, Deltanose, Duckbone, Incomparable Class, Defiant Class, and Albacore Class attack the city by shooting missiles and laser guns from their cannons. Alongside the battleships, all the U.I.M.S. Omega fighters such as the Twinhook Fighters in both types, Meteor Fighters in both types, Violet Bees, Fire Bees, Trident Fighters, and so on are raiding the city.
All U.I.M.S. Omega battleships now have the I.A.A.S. Flag Banner painted on. Its flag banner depicts a purple flag with the letters I, two As, and an S on the upper section of the flag's banner. A white circle with a black border is located below the letters on the flag, and the circle contains a black star with purple outlines. Each point of a star depicts a different subgroup, a Nihilego symbolizing the Ultra Beasts, a Meteor Type-A Fighter symbolizing the U.I.M.S. Omega, an Infected Tentacool DX symbolizing the Infected Alien Squad Deluxe, an Infected Beedrill symbolizing the Infected Bug Pokemon, and Dark Matter in its black spherical body with a ring of orange spherical blobs symbolizing the Dark Matter clan. In the middle of the star, it has a cat's eye that resembles Dark Nebula. Behind the circle, two lavender-colored beam swords cross in an x-shaped formation, to indicate that they are space pirates.
The Invasion of All Aliens Squad's organization is as big as Team Rainbow Rocket. "I wonder who is the new flagship commander of the U.I.M.S. Omega?" asked Genesect.
All of a sudden, the notorious mastermind leader, the Gooseoid, is the new flagship commander of the U.I.M.S. Omega, which is the leader of that subgroup and the leader of the entire I.A.A.S. organization. "Does this answer your question, Genesect?" said the Gooseoid, as it speaks via a monotoned text to speech program while it floats above the U.I.M.S. Omega fleet. "Let me introduce myself. I am the Gooseoid, the polygonal Canadian Goose-like robot alien, the new flagship commander of the U.I.M.S. Omega, and I am the leader of the entire I.A.A.S. fleet."
The entire fleet then goes near Dawn at Jubilife City. "Attention all lifeforms," announced the Gooseoid. "The I.A.A.S. fleet will conquer the galaxies and enslave the peoples' galaxies. Nothing will ever withstand our intergalactic empire, so prepare now, for the crowning ceremony of our I.A.A.S. Princess, Dawn. Infected Tentacruel King Overlord DX, you do the honors."
"Bow down to the Invasion of All Aliens Squad," cackled the Infected Tentacruel King Overlord DX while he uses the microphone in his UFO, "because this Star Festival has been canceled!"
The Infected Tentacruel King Overlord DX, in his UFO, presses the button to open its door on the UFO to pull out a tractor beam gun. He then gently slides the four sliders of the control panel, with his white, red, and green tentacles, to increase the tractor beam's power level. The tractor beam hums as the Infected Tentacruel King Overlord DX uses a tractor beam gun from the UFO to kidnap Dawn.
Alongside kidnapping Dawn, the Gooseoid uses the Dark Cannon by shooting out a black-colored arrow-shaped projectile, from its mouth while the robotic goose hisses, to turn Mewtwo into a trophy, like in the Subspace Emissary. Then, the aliens take the two prisoners away from the Earth. The I.A.S. DX takes Dawn away while the UB Fighters carry the Mewtwo Trophy with them.
Genesect folds into his High-Speed Flight Form and pursues the I.A.A.S. fleet while Jirachi follows Genesect. "We must rescue Dawn and Mewtwo," said Genesect. "There's no time to waste."
The Steel-Type Mythical Pokemon are above the atmosphere of the Earth. Abruptly, as the heroes are about to rescue the prisoners, they have been ambushed by the Infected Hexacool DX. "Enjoy your space flight you metalheads!" cackled the Infected Hexacool DX, as he charges the energy ball shot from the UFO's laser gun cannon. "Begone!"
A green-colored spherical energy projection fires out of the UFO's laser cannon, and upon collision towards the duo, Genesect and Jirachi then get scrambled into outer space. "Mayday! Mayday!" cried Genesect. "We've been hit!"
"No! Genesect!" cried Dawn in distress.
Meanwhile, at the Comet Observatory, the I.A.A.S. mercilessly raid the Comet Observatory as Rosalina and the helpless group of Lumas has been attacked by the aliens. As the Ultra Infected Vespiquen fires the missiles from the long antennae towards the Comet Observatory's Beacon, the Power Stars, along with the Grand Stars, scatter across the galaxies upon hitting the beacon. As a result of losing power, the Comet Observatory becomes immobile that it is stranded above the atmosphere of the Earth above the Sinnoh region. After the attack, the I.A.A.S. then leaves the Comet Observatory and the Earth.