Timeline

Monster Fighters events
Lord Vampyre, a powerful vampire, was pestered by his wife to get her a Moonstone, but when Lord Vampyre finally found it, he realized the magical power it possessed and decided to keep it for himself. If six of them were brought together (though there are actually seven in total), they would eclipse the sun and turn day into night forever, so the monsters could roam freely, and they could get to the minifigure realms. To defend the earth from this new spooky threat, Rodney Rathbone put together a band of monster fighters to retrieve the stones before Vampyre collected them to unleash their power on the world. These monster fighters include Frank Rock, Major Quinton Steele, Ann Lee, Jack McHammer, all with monster archenemies and personal vehicles. During the events of Monster Fighters, the Moonstones alerted the aliens to come and attack earth where the events of Galaxy Squad starts:

Galaxy Squad events
A mysterious race of evil alien buggoids are swarming across the galaxy, capturing civilians in cocoons and turning one planet after another into a buggoid hive. There's only one force that can stop them: Galaxy Squad, an elite unit of the galaxy's soldiers and fighter pilots who operate in four specialized task forces to save the galaxy from the alien buggoid threat.

Each team has a different strength:

Green Team: Green Team's primary skill is defense and heavy artillery.

Red Team: Red Team's expertise is speed.

Orange Team: Orange Team's main tactic is fire power.

Blue Team: Blue Team's skill is strategy and technology. Out of all the teams, it is said that they have the best tech.

After the events of Galaxy Squad, Solomon Blaze (The leader of the Blue Squadron Galaxy Squad) became an Ultra Agent.

Ultra Agents events
The theme starts in a coastal city, Astor City, with Solomon Blaze, years after his latest mission in space, alongside his four new recruits, as they train to become agents. After they completed many different tasks, they finally became part of the Ultra Agents to give the true beginning of the storyline.

The story starts with the former Ultra Agent Morgan Lux. He wanted to control the evil of Astor City, so he created the AntiMatter Staff to fight against it, but it corrupted him instead and transformed Morgan into the super villain; AntiMatter. So he started to corrupt the citizens from different districts of the city so they could bring him all he needed to create a giant device that would corrupt the entire city, so he could get rid of their "good side", which he thought it made them weak, holding them away from their potential.

Atlantis Guardians - Pharaoh's Quest - Alien Conquest events
the aliens first attempt at world domination was with the Atlantis Guardians, who are most likely alien in their nature themselves. Another attempt was when Alien Commander assisted Amset-Ra in creating the 5 Golden Treasures sought after in Pharaoh's Quest. However, after Amset-Ra was apprehended by Jake Raines and his crew, and the The Golden King was saved from the evil Atlantis Guardians, Commander Hypaxxus-8 launched a full-scale attack on Earth, preparing to abduct all the humans, use their brains as fuel for their Solar-Galactic Batteries and enslave them as mindless zombies.

However, when the ADU (Alien Defense Unit) is formed, the battle for the fate of the Earth begins. However, in the comic's climax, Hypaxxus unleashes his master plan- he first travels to the City of Atlantis and kidnaps the Golden King to use his 5 Trident Jewels as a source of power, and later goes back in time and rescues Amset-Ra, who joins him with the treasures. Together, the two of them planned to use the power to finally control the world, however they are once again upstaged when the ADU fights back and forces them to retreat. Thinking they were defeated yet again, Amset-Ra becomes furious at Hypaxxus-8 for another failure.