The series, set in the shared Marvel Universe, brings the two teams - the mutant superheroes of the X-Men and the alien freedom fighters of the Micronauts - together to face a threat that's devastating the Micronauts' home, the subatomic Microverse, but seems to originate on Earth.
At the time the miniseries was published, Claremont was the writer on Uncanny X-Men and Mantlo was writing the very end of Marvel's first licensed Micronauts series.
The X-Men and the Micronauts includes the following tropes:
- Apocalypse How: The Entity can destroy whole planets within the Microverse, as it initially demonstrates on D'Arnel. Class X: it's complete planetary annihilation, leaving nothing more than shattered rocks behind.
- Big Bad: The Entity, which has huge telepathic powers and can annihilate entire worlds within the Microverse. It's a personification of Charles Xavier's dark side.
- A Darker Me: This isn't the first time the X-Men had to deal with Xavier developing a split personality that became a villain — nor was it the last.
- Evil Costume Switch: After the Internal Reveal that Karza's mind is in Kitty's body, he switches to a purple and grey outfit that looks suitably villainous.
- Forced Orgasm: A disturbing example when Professor X falls under the control of the Entity. He turns his psychic powers on the New Mutants. In most cases that's simply Mind Control, but in Dani Moonstar's case it's heavily implied that he also caused her to orgasm to wear down her willpower, with the narration describing "psychic fingertips caressing her very soul" before she suddenly collapses on the floor "in the throes of pleasure" with an orgasmic facial expression.
- "Freaky Friday" Flip: Kitty Pride tries to phase through Baron Karza, which goes horribly wrong. Her mind ends up in Karza's body, while his ends up in hers. But Karza’s mind also retains mental control of his suit of armor, so Kitty's initially left locked inside it as a People Puppet who can't even speak.
- How Do I Shot Web?: Karza may be in Kitty's body, but he doesn't know how to control her phasing powers. Once she escapes his control, Kitty has some similar problems using his powered armor.
- Incredible Shrinking Man: Used in various combinations.
- Baron Karza arrives on earth and battles the New Mutants and X-Men while he’s doll sized.
- In the Microverse, the situation is reversed at one point - the X-Men are tiny compared to (most of) the mind-controlled Micronauts they're fighting.
- At the end of the series, the Micronauts and X-Men return to earth at doll size and fight the mind-controlled New Mutants.
- In the Back: After Baron Karza, still in Kitty's body, is captured by the Entity, his captor seems to take a Distracted by the Sexy interest in "Kitty" - so Karza steals a dagger and stabs him in the back while he's preoccupied. Unfortunately, it's not immediately fatal.
- Killed Off for Real:
- Karza's treacherous minion DeGrayde, a recurring character from the main Micronauts series, dies along with the rest of Karza's battle-fleet when the Entity turns his wrath on them.
- The Micronauts' living Bioship is killed by Magma, who's been mind-controlled by the Entity.
- Mind Control: Given the nature of the enemy, there is a lot of mind control in the series.
- The Entity's Microverse army is composed of mind controlled troops.
- The Micronauts and the X-Men both fall under the Entity's control at various points.
- Back on Earth, the New Mutants also fall prey to the Entity's mind control.
- Normal Fish in a Tiny Pond: The Entity's powers don't seem to scale down in the Microverse, so it becomes a world-destroying Outside-Context Problem. It's not as if Professor Xavier is exactly a 'normal' fish in his own universe, but in the Microverse he can almost effortlessly control or annihilate entire worlds.
- Outside-Context Problem: The Entity is a superhuman operating on a scale that's not normally seen in the Microverse. It can mind control entire worlds. It can physically destroy entire worlds with a gesture. Even Baron Karza is impressed.
- People Puppets: Kitty's trapped in Karza's body, but his body's entirely encased in his armor, which is under his mental control. She can't even speak to warn her friends.
- The Reveal: The Entity isn't a telepathic enemy trying to take control of Xavier, it is Xavier.
- Sizeshifter: As you'd expect, there's a lot of shrinking and growing in the series, but generally reliant on outside factors rather than intrinsic powers.
- Baron Karza's Rocket Punch death grip is an exception. Karza himself is trapped at doll-sized on Earth, but when he launches his hand to throttle Sunspot, it grows to a normal human scale before grasping Sunspot's throat.
- Superpowered Evil Side: The Entity is Xavier's dark side.
- Underestimating Badassery: Baron Karza's armor is almost invulnerable, so he doesn't bother dodging Wolverine's claws. A very painful mistake.
