Danny agrees to watch his crush Wendy's dog, but ends up putting the pooch in a kennel. When he gets the dog back, it's a robot! Meanwhile, Cathy is trying to come up with an "acceptable" project for an Earth science fair.

A popular new cheerleader invites everyone at school to her big party, except for the MBC kids. Cathy snags an invitation but is trapped with everyone else when the cheerleader turns into an alien intent on taking the entire school (students and building) hostage.

A demented alien with a "Santa complex" starts kidnapping Singletown kids (including Sam) and using them as elves in his "toy factory." Meanwhile, Mark and Danny have to work together planning the school's holiday party (to try and impress Wendy).

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.

Sam tries to simultaneously run a school bake sale, and help Cathy babysit for a very hungry toddler, who turns out to be a "dangerous" eater alien. Danny and Chris, meanwhile, must compete against Mark's extravagant efforts to ruin their bake sale.

A new sewer tunnel threatens the MBC's secret ship which is buried in Cathy's backyard. Especially when it turns out the sewer workers are actually sticky aliens, hunting for the MBC. Meanwhile, Mr. Fuster leads a science field trip to explore the infrastructure of the city.

The MBC goes up against a bizarre alien named Proscar who loves to play games. They must stop him from turning the entire town square into a giant game board and destroying the town. Meanwhile, Danny is stuck in detention with Jeremy.

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).

Several students, including Sam, are suddenly slavishly devoted to Gilbert, one of the nerdiest kids in school. Gilbert turns out to be an alien using student labor to process his vast comic book collection. Meanwhile, Cathy discovers comics for the first time, and can't stop acting (and speaking) like her favorite superhero.

Cathy invites the star of an alien "nature show" to Earth so he can document the planet's wild creatures. But the only "creatures" the alien wants to film are humans - and he has an evil plan to make them all look extra "wild" and dangerous.

Cathy gets detention only to find that the teacher in charge is an evil alien! Chris, Sam, and Danny attempt to cause "trouble" and get detention as well to assist Cathy in defeating the Sticky teacher.

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.

Feeling under appreciated, Chris accepts an intergalactic talent manager's offer to make him star but ends up attracting the wrath of a vicious, competing, alien talent agent. Meanwhile, Cathy gets the lead in the school play.

The MBC battles a race of ferocious, bug-sized aliens who are trying to chase all the humans out of Singletown. Meanwhile, Principal Rollins pays a visit to Cathy's house to meet with Mr. Smith and, surprisingly, they really hit it o

Mr. Smith entrusts the gang to protect the "forget me stone" - an ordinary looking rock that causes people to lose a wide range of memories. An evil morpher is out to get the stone in the hopes of erasing people's memories (and forgetting his crimes).

Each year Principal Rollins selects one student to act as "principal for the day" and this year it's Danny. Principal Danny gets totally carried away and it seems like the only one who thinks he's doing a good job is Wendy.

The MBC protects Cathy's mind-reading, alien cousin Elton from the Pincher Bots that want to capture him. In the process, Elton reads Danny's mind and accidentally reveals one of his most embarrassing secrets to the entire school.

The kids must take action when Mark mistakes Mr. Smith's universal communication device for his cellphone, and almost starts an intergalactic war with his rude remarks to the alien callers. Cathy, meanwhile, has discovered the Earth concept of phone gossip.

n an effort to impress Wendy, Danny ventures into a really scary haunted house... and gets trapped. The MBC goes inside to rescue Danny and discovers that the house is owned by a friendly morpher alien and his pet manta-puppy.

The MBC are charged with protecting an alien ruler who is a tiny flower, but Jeremy naively takes the plant as a gift for his secret crush (Cathy). Meanwhile, Sam gets addicted to Chris' video game.

Various things start disappearing around town, but nobody sees where they're going. By slowing down surveillance cameras, the MBC discovers that a "speed morpher" is stealing all of Singletown's technology. If he isn't stopped, the town will collapse into chaos - and the MBC kids will all lose their new part-time jobs.

While looking through some old MBC artifacts Chris inadvertently brings to life a statue of Addison Single that stands in front of the school. It turns out that Addison (thought to be the town founder) was actually an evil alien that was "statue-ized" by a colonial version of the MBC.

The MBC are asked to take over Mr. Smith's orientation seminar for new alien arrivals to Singletown. However, their efforts are repeatedly sabotaged by one of their "students." Meanwhile, Cathy mysteriously goes on a date with Jeremy

The demands of the MBC force Danny to duck out of several "tough guy" challenges by a new kid at school (who turns out to be an alien intent on disrupting the MBC's teamwork). Meanwhile, Cathy runs for student council president.

The MBC goes up against Herpitilius, a giant frog from outer space. Herpitilius was originally an earth frog who nearly got cooked up in a French restaurant, but managed to escape. He was abducted by aliens and turned into a super frog, and now he's returned to round up his earth brethren and exact his revenge.