In the year 2023, construction has began on the first lunar colony. During the process of construction, Rita Repulsa's prison is discovered and opened, causing her ship to materialize on the moon, amalgamating with the various construction and transportation equipment to become her Moon Base. Sensing her old enemy Zordon on the planet below, Rita begins utilizing her minions to attack Earth and recover any Zeo Crystals they can find. The sleepy desert town of Angel Grove has sprung up around the mountains covering Zordon's citadel, and as such it becomes a primary focus of Rita's attacks. Fortunately, the Citadel was discovered by five overbearing and overemotional humans, who were exploring an old mine shaft on a dare they received in detention. Their names were Jason Lee Scott, Kimberly Ann Hart, Billy Cranston, Trini Kwan, and Zack Taylor. After discovering Zordon and reactivating Alpha 5, they are entrusted with the five remaining Power Morphers and their accompanying Zords to become the new Mighty Morphin Power Rangers. While initially reluctant to take up the mantel for a variety of reasons, they eventually came together when Rita sent down her two minions Goldar and Scorpina attack the city. The first of many battles between Rita and the Power Rangers.
Eventually, Rita got the idea to create her own Rangers using the three Power Morphers she still possessed. She found the perfect candidates in Tommy Oliver and his goons Bulk and Skull, a group of high school bullies who also were responsible for the low level gang activity in Angel Grove. However, while Bulk and Skull were pure evil and happily served Rita in exchange for her promise of power, Tommy had a heart of gold he worked very hard to suppress. While initially gleefully taking on the Power Rangers, the increasing scale of her activities eventually lead him to rebel against Rita, working with the Power Rangers for a few episodes leading up to the first season finale. In which Rita finally busts out the Cyclopsis Zord after finding it's container hidden within her ship. Tommy eventually sacrifices himself to defeat Cyclopsis by attempting to merge with it, crippling the Zord, causing extreme damage to the Dragonzord, and vaporizing his body. The day is saved at great cost, and Rita retreats for now.
The second season begins with a few events as catalyst. One, Rita is able to finally repair the Dragonzord, but not Cyclopsis, and recruits a girl named Katherine Hillard to replace Tommy as the Green Ranger. Two, Tommy Oliver returns! He awakens within the Morphin Grid and goes on a spiritual vision quest with Saba, his spirit guide. Eventually he returns as the White Ranger, commanding the new Brachiosaurus Zord (the powerful Zord Ninjor built for the White Ranger, should one be ever proven worthy of his mother's coin). We also get a new villain in this season! The psychopathic Joker-esque Ivan Ooze, brought in by Rita to try to destroy the Rangers, who she equips with the old Hornitor Zord (though not as powerful as it used to be).
Across the ensuing seasons, a handful of other villains emerge to challenge the Rangers. The Machine Empire, Count Dregon, Captain Divatox and her crew, Ransik (the Genghis Khan of the future), the Dark Demon Lokar, the insect queen Trakeena, and the Venjix computer virus. They also meat many allies, namely the powerful Masked Rider, the Time Force Rangers of the future, and a certain group of radical reptiles with an affinity for Italian cuisine.
Eventually, while scrounging around the moon base for parts, Squatt and Baboo discover and accidentally release Lord Zedd. Rita falls at her master's feet, and he compliments her for keeping up the fight. He decides to swiftly deploy his own Zord, Serpentera, and attacks Angel Grove with the Rita Rangers as backup. The Rangers fight valiantly, but Serpentera is too strong for even these 6 zords by themselves and the Ultra Dinozord is destroyed beyond the zord's capacity to heal. When the rangers attempt to summon them all they get is the rubble. Zordon tells the Rangers of Ninjor and Dulcea, though only in part, and they set off into space to find them and get their Zords repaired. This also draws Lord Zedd away from Earth as he attempts to reclaim the Power Morphers. To protect the earth in their stead, The Rangers grant a portion of their power to five of their friends, Rocky DeSantos, Tanya Sloan, Justin Stewart, Aisha Campbell, and Adam Park to become the Zeo Rangers. They make it as far as a small spaceport just outside the Oort Cloud before their ship breaks down. While there they are attacked by the forces of the Dark Queen Astromena, who is the current ruler of the galaxy in the absence of Lord Zedd. They are able to hold her troopers off, but are unable to fight the giant monster they deploy, and are rescued by a strange man named Trey of Triforia. An alien with multiple personality disorder who was inspired by the stories of the Power Rangers to become a force for good in the galaxy with his Golden Staff of Power, stylizing himself as the "Gold Ranger" with his spaceship Pyramidas acting as his "Zord". Trey becomes their guide across the universe as they search for Ninjor and Dulcea and evade Astronema's forces, as well as Lord Zedd.
Eventually the two are found and reluctantly work together to forge new Zords, the Thunderzords, after some cajoling from Tommy, Saba, and an astrally projected Zordon. The Rangers also learn the final hidden pieces of backstory. As they are preparing to return to Earth, Lord Zedd attacks Ninjor's planet with Serpentera. Thankfully the Ultra Thunderzord, along with some help from Ninjor: Battle Mode and Dulcea as the Brown Ranger, are able to defeat and destroy Serpentera and the Rangers return home. Though Zedd is still a threat, even without his mighty war Zord.
We then get maybe one or two seasons with the Thunderzords, including one centering around Lord Drakken. I'm also contemplating a potential VR Troopers crossover and a crossover with the Sentai Spider-Man show (though given the Americanization Saban Treatment).