Ivan Ooze was locked away in a Hyperlock chamber 6000 years ago by a previous team of Rangers. When this chamber was dug up by a construction crew, Lord Zedd thought he could free Ivan and together they would destroy the Rangers and Zordon.
While the Rangers were distracted by Ivan's Oozemen, Ivan managed to get into the Command Center and destroy it, taking the Rangers' powers and almost killing Zordon. To regain their powers, the Rangers needed to travel to the planet Phadoes.
While they were gone, Ivan trapped Zedd and Rita in a snow globe, took over their army and enslaved the parents of Angel Grove to dig up his Ectomorphicon Machines, Scorpitron and Hornetor. When the Rangers returned, Hornitor and Scorpitron were destroying the city.
They called upon their new Ninjeti Zords. And destroyed Scorpitron. Ivan put himself in Hornitor making the machine change shape and gain strength. The Rangers put together the Ninjeti Megazord and battled Ivan.
The battle went into space, the Rangers were struggling in the fight. They then managed to kick Ivan in the path of Ryan's comet, the collision destroyed Ivan and undid all of his spells, freeing Angel Grove's parents and Zedd and Rita.
"From this moment forth, the world as you know it shall cease to exist! Welcome to my nightmare!"