Hugo is appointed a job in which he has to make peace between two planets before they go to war. He is given a galactic communicator that looks like a cellphone. Due to Chris' curiosity, he takes the communicator and loses it when he crashes into Mark and the devices get mixed up. Mark keeps getting the calls meant for Hugo and insults Zubin. The two planets go to war on Earth. Soon after the space ships arrive, Chris and Cathy get back the communicator and make peace between the planets. (this is episode 04 on DisneyXD USA)
Sam helps babysit toddler Tina, a Pythenor Eater alien, for Cathy while she still has to help with the bake sale benefiting hungry whales with Chris and Danny, making her go back and forth to each job. With all the stress, Sam accidentally feeds Tina Glusock crackers, an alien food that Pythenor Eaters shouldn't eat because it puts them on an eating rampage! Meanwhile, Chris and Danny are having trouble with Mark's Everyday Airlift Bake Sale raising money for Mark to have a helicopter. Tina gets to the school and starts eating all the bake sale goods but is momentarily stopped by a Floater Disk, but she can even eat food without touching it. Hugo tells them that the only way to stop this rampage is to get the taste of Glusock out of her mouth, so they use John's "Dumdy Dum" delectable dispenser, which produces bad tasting cookies and stops the little Pythenor Eater. (this is episode 05 on DisneyXD USA)
Cathy gets detention when she fights with Mr. Fusster about intelligent life other than humans. The detention teacher is Mr. Gluten and it turns out to be a Sticky glue alien. To solve this problem, Danny says to fight the alien they should all get detention, which Chris and Sam don't like since they never get detention, unlike Danny. Chris shows up the next day with a gangster look, but still is finding trouble getting detention. Cathy and Sam look for Mr. Gluten's file and escape once they find it. At lunch, Mr. Gluten turns into the lunch lady and Chris and Danny call for help. When Mr. Gluten escapes, Sam tackles the real lunch lady and gets detention. At detention, Sam finds out the real Mr. Gluten is on vacation. When the Sticky attacks and tells Cathy and Sam he is recruiting alien workers and that he is gathering Rhapsodians A.K.A., Cathy to work for him. Just as he is about to capture Cathy, the boys throw a stink bomb and the Sticky escapes into the forest. The MBC Members follow him and stop him by using a Rhapsodian puzzle stick that Danny sets between two trees to trip him and knock him down. Chris hacks into the student files and clears their detentions, so that Cathy and Sam have clear student records. (this is episode 06 on DisneyXD USA)
Wendy asks Danny to look after her dog named Matisse, while she is on a trip to the mountains. In order to impress Wendy, Danny signs Matisse to behavior-correction school where Matisse is replaced with moto-dog, things start to get complicated and it's up to The MBC Members to save Single Town from Matisse moto-clones. (this is episode 02 on DisneyXD USA)
The MBC Members Members get a new mission. They must guard The Flower King named Petalia XIV, who is in the form of a flower until ambassadors from his planet arrive. Meanwhile, Jeremy is trying to impress Cathy by presenting her a flower. He accidentally mistakes Petalia for one and kidnaps him. Now, the MBC Members have to deal with both robots sent to capture Petalia and finding Petalia himself.
A catchy song by an alien rock band literally takes over students' minds (including Danny), and makes them unwittingly construct a doomsday device during a Battle of the Bands concert. The MBC must form their own band to enter the contest. Meanwhile, Cathy looks for the perfect birthday gift for her grandfather.
The MBC Members try to use the interplanetary transporter to send several captured aliens to the galactic authorities, which requires the retinal scan of all of The MBC Members to complete, but Danny is running late. The transport fails, which results in a battle with accidentally freed aliens. Meanwhile, Cathy prepares herself, with Sam's help, for a Student Council President, but both she and Danny, in a matter of coolness, face opposition of new tough schoolboy, Brian. Now, it is up to The MBC Members to investigate why Brian challenged Danny and Cathy. (this is episode 10 for DisneyXD USA)
In the cafe, The MBC Members fights a lizard-like alien, who is trying to kill a stylish guy. The lizard alien escapes, and The MBC Members meet Stanley Caminski, one of the galaxy's most successful superstar manager. For saving his life he explains that attacking alien was his unsuccessful competitor, whose stars aren't popular. Stanley offers The MBC Members his assistance so they can become stars too. Everyone agrees, but Hugo says no, because Monster Buster Club is a secret society and must not be revealed. Chris, however, secretly calls Stanley and agrees to participate in commercials. Meanwhile, Cathy auditions for the school play, "Romeo and Juliet" and turns out to be an amazing actress, so she wins the part and must prepare for opening night. Wedge, the lizard alien, is looking to kill every superstar who works with Stanley. Now, with Cathy too busy, and obsessed, preparing for the school play, and Chris not wanting to believe that Wedge is after him, it is up to Sam, Danny and John to find Wedge before he strikes. (this is episode 09 for DisneyXD USA)
The MBC won't let John become an official member of the club, so he joins a mysterious, new, alien-fighting group in town called, "The Monster BEATERS Club" (who are actually evil aliens in disguise). Meanwhile, Principal Rollin forces Danny, Chris, Sam, and Cathy to join unpopular school clubs (like the knitting club and tap-dancing club).(this is episode 12 for DisneyXD USA)
Cathy and Sam are angry about seeing so few comic books about women. While a mysterious man runs out of the local comic book shop, they pursue him but he gets away. Meanwhile a strange new boy appears at their school, trying to make kids follow his orders to prepare all his comic book collection from the other planet to be stored on the Earth, making Sam follow his orders too. With Cathy busy imitating one of the comic book heroines, will The MBC Members be able to save kids from the mysterious boy alien? (this is episode 11 for DisneyXD USA)
Sam volunteers to prepare a celebration of the day, when city was founded by a man named Addison Single. Cathy, however, proclaims Addison was an alien who tried to make this city for aliens. Sam refuses to believe it, but soon deep in the abandoned MBC storage beneath their clubhouse, where Chris accidentally activates a violet gemstone bringing the statue of Addison Single to life, which is revealed later that it is not a statue, it's the founder himself. Now The MBC Members must stop the statue from turning all citizens into stone, while keeping them busy so that they will not notice. (this is episode 15 on DisneyXD USA)
The MBC Members take a fun-ride through the underground tunnels when the pipes begin to shake. However, they discover that road workers are causing it, but soon they turn out to be following new plans for digging new sewers. Meanwhile, Mr. Fusster takes the class sightseeing in the sewers. The MBC Members realize that class may discover club's tunnels which intersects with the sewers. Sam decides to scare everyone off so their club will remain undiscovered. However, things get worse when the strange "road worker" turns out to be an alien who tries to "suck" the entire town into the big prototype of MBC's tractor beam using the club's net of tunnels. Will The MBC Members be able to stop him before he succeeds? (this is episode 16 on DisneyXD USA)
Chris has a part time job spring cleaning a shop. His boss nags him to make sure he finish or he'll be fired. Meanwhile, his friends come in to visit and suddenly their communicators detects an alien coming into the shop and The MBC Members try to power up, but they are not as fast as him. In only a few seconds, all items in the shop disappear and his boss nags him again and suspects that his friends stole all the items and must either get all the items back to the shop or pay for them by 6 pm or else he'll be in big trouble. A second later, Danny's video game is also stolen. Soon after that Sam, Danny and Cathy are going for a part time job try to repay the money for the stolen items, but later, all of Single Town's electronic devices disappear, including the MBC container! Can The MBC Members find this Speed Morpher alien before Single Town is in chaos? (this is episode 13 on DisneyXD USA)
It is time to start a snow holiday and Chris, who loves the winter holidays, tries to figure out what kind of present he is going to get. Cathy doesn't know about Santa because she does not know that Earth also has snow day. Trouble comes in the form of Roy's present when it is revealed that it is a tracker planted by Dingle, an alien disguised as a Santa who is trying to bring all the kids, including Sam, to an old air container, making it look like he is trying to take the kids hostage. But afterwards, it is revealed that Dingle was just trying to get the kids to accept his presents. (this is episode 23 on DisneyXD USA)
It is a good afternoon and everyone is coming out for a walk and to study. Danny is skateboarding and showing off while Chris is working on his project, thinking he can finish before night falls. A bug scout sees everyone and Chris tries to drive him away. The bug ends up throwing him and causing an accident with Danny on the skateboard park, making Mark laugh at him. Soon, as they walk down the street, a swarm of bugs attacks The MBC Members. Danny catches a General bug, named General Louse but the swarm continue to attack forcing them to retreat back to their club house. Cathy tells everyone that Hugo is seeing Principal Rollins and she thinks she'll be getting detention. On the street, they are attacked by a swarm of bugs again. After a while, it reveals it's an alien bug and The MBC Members find out that their bug queen is coming to lay her eggs. Can they stop the queen before she arrives? (this is episode 14 on DisneyXD USA)
One quiet single night in Single Town, Hugo and his plant playing a cards game in his house when there's trouble, an alien called Glor Glenemore is there to steal the Forget-Me-Stone, which causes chaos when it is activated and erases the memories of those who touch it. When the Glor Glenemore, who tries stealing The Forget-Me-Stone, suddenly he drops it in the middle of Single Town Middle School. Mark finds the stone and touches it, erasing his memories and even worse when he brings to school and lets everybody in the school touch it and erase their memories. Can The MBC Members track down Glor Glenemore and help everyone to recover their memories every people before all were turn into chaos? (this is episode 17 on DisneyXD USA)
It is another single night in Single Town while the MBC Members are chasing a small Robotic machine, that has stolen electronic devices with the car, while only halfway into the chase, their arsenal has no more power so the small Robotic machine escapes. When they're back at their club house, the power is very low and Sam shuts it off or else no more power to recover it, but it will take more than a month to recharge it. She worries that there will doom if it doesn't recharge in less than a week, the whole world will be the alien's home. Suddenly, Hugo invites the MBC Members, including his granddaughter, Cathy, to go camping. So they go to Rocky Mountains Hill, to find an energy flower (The Mobato Flower) which can restore the club in full power, which only grows every four centuries. At night a monster appears at their camping zone and eats everything in the backpack. They must overcome the monster and cross mountain after mountain to claim the Mobato Flower, but the monster reaches it first and tries to claim it, The MBC Members have no choice but to fight for the flower. The monster is revealed to be just a paper machine with a small Robotic machine inside. The MBC Members bring back the flower to restore their club to normal. (this is episode 18 on DisneyXD USA)
It's Halloween and all the kids in Single Town are going trick-or-treating. Mark challenges Danny to go into the haunted house alone. In the end, Danny would be the first kid inside the haunted house. When he goes inside, there are a lot of spooky things happening to him: books flying around, the wall moving itself, he goes into the room and was trapped by the sticky on the floor. He tried to escape, but it didn't work. He alerts the other MBC members to save him. While Danny is trapped inside the haunted house, Chris, Sam and Cathy are going Trick or Treating, when suddenly their communicators get a transmission from Danny. They speed their way to the haunted house to save him. Finally, they reach Danny and try to save by using arsenal to break free from the sticky, which he has hold. When suddenly the floor is alive by itself, everyone is trying to get ready for battle, but after a while it reveals itself as a giant alien pet dog named Moppy, who has been lost on earth many years ago. The aliens of the Nix pet told them about the situation, his pet puppy's space ship only arrives on Halloween for their return to their planet. If this year ends they have to wait another year and he tells The MBC Members that the spaceship arrives somewhere in the single people home swimming pool. So The MBC Members hurry up and carry Moppy, and speed their way to the space ship with the help of John, they're aware of people in Single Town will see the alien's pet dog. After all a long way, they finally reach the pool, but Moppy refused to go in the space ship. So, Danny uses his skill to attract the dog to space ship, Nix is very proud of The MBC Members and thanks them for bringing back his pet to their space ship. He will meet them again on another Halloween and they fly back to their planet. (this is episode 19 on DisneyXD USA)
Danny is picked to be principal for the day, and has great ideas on how to improve the school. However, an evil dinosaur-like alien pretends to be Wendy, and attacks Chris and Cathy. Meanwhile, Sam is trapped by the real Wendy, who wants to be 'Miss First Aid of Single Town Middle School' when she falls over while running after her bus. (this is episode 20 on DisneyXD USA)
A mutated Earth frog (Herptilius) comes to Earth to seek vengeance on a chef that nearly cooked him years ago. Coincidentally, the chef turns out to be a replacement of Mr. Fusster (Who is on holiday) for science. The MBC Members must stop the frog, but he's invincible against anything, apart his weakness of Earth flies. (this is episode 21 on DisneyXD USA)
Cathy invites her favorite TV star to Earth (Outcracker), who tries to get good footage of dangerous stunts, which is disastrous. First, he tries to attack Mark with a robot Juice machine. Then, he has Wendy holding on for dear life when he takes off the bottom of her hot air balloon. Danny then jumps from the car in the air and saves Wendy the 'Old Fashioned way.' After that, he releases an army of camerabots at the satellite station. (this is episode 22 on DisneyXD USA)
The seminar saboteur turns out to be the son of Addison Single, the corrupt alien founder of Singletown. In an effort to turn Singletown into an "alien paradise," the son has unleashed a morph jammer, that prevents local aliens, including Cathy, from retaining their human form.(this is episode 25 on DisneyXD USA)
Little John inadvertently subjects the MBC to the effects of his truth ray, causing them to suffer strange physical effects whenever they lie. This complicates their efforts to subdue an intergalactic villain. Meanwhile, Danny gets an opportunity to work with Wendy on an assignment - "Life on Other Planets: Fact or Fiction." But his inability to lie causes big problems for him as well.
When Danny and Sam mess up a few assignments, the IGA commander sends down two droids to assist the MBC. But, while Chris and Cathy get along with the new recruits, Danny and Sam suspect that they're up to no good. Meanwhile, Mr. Smith recruits the MBC to help him plan Cathy's "Sweet 250" birthday party.
A group of bubblegum-like aliens come to earth to seek refuge from their planet (Bagumblia) which is suffering from global cooling. Their leader is angered when Danny inadvertently chews him and declares war on humanity, taking Mark as their hostage. The Baglumbians threaten to unleash their hideous mastication monster on Mark, and the MBC must leap into action to protect him.
The MBC investigates a strange caveman-like alien that has come to earth and is reaking havoc around the school. Krog's destruction seems to be random, until they discover what he's really after - the hand of Principal Rollins! Meanwhile, when the MBC decides that Sam needs to "lighten up" a bit, Cathy takes it upon herself to try some strange Rhapsodian techniques.
When Singletown experiences some strange weather patterns, the MBC discovers that the entire town is covered with an alien Jellynerp. The creature was placed there by the local weatherman - actually an alien - who is tired of reporting the weather and wants it to be the same every day. A sound plan, except for one minor detail: now the Jellynerp is hungry and it's starting to eat the town!
The MBC unearths a time capsule left behind by the original MBC, warning of an attack that is due to take place in the future. The MBC receives a series of encrypted clues, which they must follow in order to avert certain disaster - in the form of all the aliens being released from the containment grid! Meanwhile, Mr. Smith's sister Frida shows up for an unexpected visit.
When Singletown goes into an unexpected deep freeze, the MBC suspects alien activity. It turns out that Pizmo, a reformed eater alien, has turned the town into his own personal workout facility. He's created a cooling machine so that he won't sweat during his insane workouts. But now the cooling machine is out of control and threatens to throw Singletown into another ice age.
When Jeremy accidentally comes in contact with an alien substance, he undergoes a strange transformation - turning into a hideous monster whenever he sees anything Rhapsodian. The MBC must figure out how to reverse the effects before Jeremy destroys everything. Meanwhile, Sam gets blamed for injuring Mark and Rollins forces her to assist Mark with his hideous science project.
When the MBC breaks the record for "monsters busted in one month" they receive a reward from the IGA commander - flying lessons on the ultra-cool V-9 spacecraft. But, as it turns out, the flying lessons are all a ruse. It's a plot by their old friend Herptilius to kidnap the MBC and ship them off to an intergalactic barbecue... where they will be the main course!
Glutin the Sticky alien returns to Singletown Middle School and he's out to bag himself a Rhapsodian. The MBC immediately assumes he's after Cathy, but they're mistaken. You see, during a mishap in Fuster's class Cathy's powers have inadvertently been transferred to Wendy! The MBC has to try and reverse the effects before Wendy gets out of the school... or gets captured by Glutin!
Mr. Smith surprises the MBC with a special performance by a great magician - Rhubarb the Remarkable! However, the gang is shocked to learn that Rhubarb is actually a "reformed" bad guy that they defeated in episode 10 - Wedge, the talent agent. They're suspicious of Wedge right from the start... and with good reason.
The MBC Members are to take well care of the planet Nebulak and Hugo has to make peace inside by making a house of cards. The catch is that the planet looks like a bowling ball and an egg to an ugly alien. In the end, The MBC Members defeat the alien, but Mark was watching so they made it all seem fake. Finally Hugo makes peace and gets a trophy, but has to give it to Mark. (this is episode 41 on DisneyXD USA)
Sam and Danny were trying to connect with their past selves. But at the same time things are changing in the future. As Sam and Danny are in the past Chris and Cathy try to stop the aliens from taking over like Danny saw in first part. Meanwhile the Commander is trying to get the key from one of his 37 stomachs and get the MBC back. As soon as Sam and Danny get the video camera they hand back to when they were in the clubhouse. So now Singletown is now safe. (this is episode 43 on DisneyXD USA)
When the students get to school, surprises start happening everywhere. When Mr. Fusster gets a broom, an alien from Numbare, Mimi, tries to get Mr. Fusster to marry her. The MBC save Mr. Fusster, but Mimi is getting mad. They see Mr. Fusster buying texido shoes. Cathy invites Mr. Smith to the "fake" wedding being used to bust Mimi. When Mr. Fusster and Mimi are dancing, they notice Mr. Fusster is using alien moves. They bust Mimi but when Mr. Fusster questions the wedding the MBC thinks that Mr. Fusster might be an alien because his unuasual knowledge of Numbarians. (this is episode 44 on DisneyXD USA)
Jeremy asks Cathy to be his date to the earthclips, and thinks she said yes. At the clubhouse, the Commander gives Cathy a test she needs to pass in order to stay in the MBC. Mr.Smith, Chris, Sam, and Danny watch the earthclips, but last longer than it was said to be. They spot a spaceship and an alien who is controlling everyone's minds. They find out he was stopped by other MBC teams over the years. Cathy's mind leads her to a special magazine that is in Jeremy's room. Sam is stuck in a rocket sent to destroy the sun. Jeremy and Cathy work on a way to help Sam, spin! Chris and Danny dance to hard for the machine, and it blows up. Sam returns home and everyone wakes up from there trance. (this is episode 45 on DisneyXD USA)
A clean freak alien has come to Singletown to clean all the "mess" at least what he calls mess. But when he starts throwing all the supposed "trash" into a vortex and decides that he wants to get rid of humans. Meanwhile Cathy is addicted to ordering stuff from Singletown advertisements for only a penny leaving her home filled with boxes. So Chris leads the clean freak alien to Cathy's house where he organizes all the boxes. There Sam vacuvates him and the town is saved once again. (this is episode 46 on DisneyXD USA)
It all started with Gilbert (from comic book heroes) who made trouble by bringing from his planet a laughing machine called a 'Ha Ha Honker' which hit Matisse. So now Matisse is going around town making everyone laugh. Now the MBC have to stop the laughing before it hits them, but it was too late because while being at the school Matisse found Sam and Chris and made them both laugh. Meanwhile, Gilbert has landed on earth trying to get the Ha Ha Honker back and keep Singletown safe. Cathy is later blasted, but instead of laughing, crying. Matisse then get the 'Ha Ha Honker stuck in a satellite dish causing a cloud that spread the effects all over town. In the end it's up to Danny to save Singletown and his friends. (this is episode 47 on DisneyXD USA)
King Petalia is back or should i say former King Petalia is back and he is in Single Town to learn how to dance from the only person who ever got him to dance "Jeremy". But the problem is at first when he comes to Single Town he says that the clipper bots are after him but instead they are working for him. The MBC finds out and learn that to get Jeremy to teach him how to dance he's using a machine that sucks Jeremy's life force[while Jeremy is clueless, thinking that he's on some kind of hidden camera dance show]. The MBC later defeats him and they vacuvate him. (this is episode 48 on DisneyXD USA)
Cathy's Aunt Freeda and her new husband Moochie show up unexpectedly to Single Town because Moochie has clingindwarfers disease(obsessed singing disorder) and Mr. Smiths garden is the only place that has the cure. But when Principal Rollins sees Moochie sing she asks him to sing the new school anthem in front of everyone only when Moochie sings with a microphone it gets so loud that things shake and break so the MBC tries to stop him from singing but they have no luck. Just in time Freeda shows up with the cure and gives it to Moochie and Single Town is safe one again. (this is episode 49 on DisneyXD USA)
Doudo, the worshiping alien from "It's No Good to be King", who revered Chris as a king, returns to Singletown and asks Sam to make believe she's a princess, in order to protect a real alien princess hunted by some distant alien warrior looking like a huge pig. Sam hesitates, but accepts. From then on, she has to act exactly like an authentic princess does : she must learn to walk, to talk, to position herself, to smile just like a member of the royal family would. Notably, she's not allowed by Doudo to do anything, including help her friends to hunt down aliens. And all the good deeds Sam had to complete in her schedule – do the shopping for an old lady, help clean the park and so on – are transferred to Chris, Cathy and Danny. Meanwhile, the alien keep on looking for the alien princess, and devouring everything he can, because of his tremendous appetite. When Doudo realizes that the pig-warrior is getting closer, he does all he can to stop him. As Sam decides she can't bear the make-believe any longer, and that she will go help her friends to bust the pig-warrior, ignoring Doudo's warnings, this one traps Sam in a ball and goes to fight his enemy. Once Sam finally gets out of the ball, she joins the rest of the team for the hunt. But the pig-warrior finds her and understands she's no princess. He then manages to locate the real princess, captures her and tries to escape, but the MBC can trap him on the skate ramp in the park and vacuvate him. In the end, Sam confesses she'll never "play the princess" again, as she's really not made for that. (this is episode 51 on DisneyXD USA)
The MBC is infected by an alien virus. In order to quarantine them, the clubhouse was sent to outer space. This episode is made up mostly of flashbacks on the MBC's adventures showing how they got infected in the first place, but also focusing on the personalities of the team, and also notably insisting on the importance of team work to solve problems (many sequences show how MBC could capture aliens on uniting their strengths). Mr. Smith then uses his Rhapsodian healing powers to cure Danny, Chris and Sam, but fails in curing Cathy. It appears that the virus can't be extracted from Cathy's human body : so she has to transform back into her Rhapsodian form and concentrate hard to expel the virus. Once it's out of her, Cathy turns back into human & the team blasts the virus, which automatically ends quarantine. The clubhouse can now safely return to Earth. Note: This is the series finale. (this is episode 52 on DisneyXD USA)