Prepare now for the info dump!
M'kay originally Saban was gonna take Jetman and, adapt that series for America. Then Zyuranger came along and, they decided to go with that instead. Super Sentai started in 1975 with a series called Goranger. It has continued on until today and, is still creating new Super Sentai teams. The latest being Shinkenger. Also if you're interested in more surreal experiences you could check out Dairanger. Dairanger's most noted character is the white ranger. Who was adapted for the character Tommy in Power Rangers. Kou or Kibaranger is actually a kid in the original source material. The rest of the Dairanger task force is made up of un-adapted rangers. Saban didn't want to change the Power Ranger team suit entirely becuase of fear kids wouldn't like the change. So the only reason for the change over to using Kakuranger and, Ohranger footage was becuase they ran out of Zyuranger footage to adapt. So they were paying Toei to create more. Meanwhile they wanted to transition the Zords quicker so they spliced the original Megazord/Zyuranger out of the footage they ordered and, spliced in the Thunderzord/Dairanger footage for the zord battles. This footage has since been called Zyu2. It's been theorized that Toei was thinking of making a second Zyuranger season with the footage but, abandoned the idea. Just a rumor thus far. Futhermore there was actually a different pilot filmed for MMPR with a different actress for Trini and, Zordon was called Zoltar. It's up on Youtube if you want to watch it. There's two versions if you search for "Power Rangers unaired pilot" you can see the original version at the top of the search list. The second version was aired as a special with Austin St. John and, Walter Jones. With some violence cut down. It also takes place in a bowling alley. It's been rumored that there actually was a pilot shot for the Jetman footage. If there was it hasn't been leaked at all. About Dairanger in the PR: Lost Galaxy season it was planned to use the unused footage or, suits as the "Ancient Warriors" for Power Rangers. That plan was abandoned for some reason that I don't know. Kakuranger was the source footage for the Alien rangers, some of MMPR's monsters, and Ninjor. From Ohranger onwards it's basically a season to season adaptation from there. In Ohranger the gold ranger is played by a kid too named Riki/King Ranger. The gold ranger was adapted for Jason and, Trey in Zeo. After Time Force/Timeranger Disney bought the Power Rangers series and, continued it with Wild Force until today. The current season of Power Rangers deals with the death of all but one city in the entire world.
End of info dump.