I've been watching Battle Fever J, my first Super Sentai
Only the first because Himitsu Sentai Gorenger and JAKQ don't have complete subs, to my knowledge or ability to search for them at least.
I'm kind of surprised they had so many of the important PR-like elements down so early. The Battle Fever Robo is actually kind of interesting considering it's the first real "Zord" of the series - it used a variety of samurai weapons depending on which ones got knocked out of its hands by the enemy robots. Of course, it was a one-piece robot, from what I read the idea of interlinking mechs was first introduced in Taiyo Sentai Sun Vulcan.
Also interesting is how because they didn't quite have the concept of "growing monsters" yet, each of the giant monsters was actually a giant robot version that fought alongside the "monster of the week" - kind of hard to explain unless you've seen it yourself.
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