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.

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!

The MBC investigates when people start mysteriously disappearing all over town. It turns out to be the work of "Beady" - the evil twin brother of the speed morpher, Speedy. He's determined to set up a museum-like exhibit of "The Galaxy's Strangest Creatures" and tour around the universe.

When an alien named Doodo mistakes Chris for an intergalactic Emperor, Chris goes along with it, thinking it will be fun. But things quickly get out of hand when the MBC discovers that there is an evil alien named Krungnar who is out to mandelbark the emperor's flaggins.

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.

An evil Lizard creature (hell bent on eating the precious Mobotto Flower) performs an alien mind meld on Danny and the two end up switching brains. While Danny tries desperately to warn the MBC, he falls into the clutches of Roy and Ralph who try and make him into a circus lizard.

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!

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)

Mark finds a "training tape" of the MBC kids and tells everyone in school about the alien-fighting club. With their secret discovered, the MBC kids are idolized by some classmates and jealously mocked by others. Several vengeful aliens also learn the kids' identities and set out to destroy them.

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)

Students in Singletown Middle School are thrilled to participate in the pet show that the school has organized. This year's jury is the famous Morag...but is she really famous? Why is it that no one has heard of her before? And what is the secret plan she's trying to pull up?

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)