Not every color-coded group of costumed heroes is a "Power Rangers knockoff." Far from it, in fact.

The concept, referred to as "sentai," is believed to have originated with <a href="http://en.wikipedia.org/wiki/Gatchaman">Gatchaman</a> in 1972, and it spread from there until it became firmly instilled in Japanese pop culture. This was largely facilitated by the <a href="http://en.wikipedia.org/wiki/Super_Sentai">Super Sentai</a> franchise, which began in 1975 and continues to produce new shows to this day. What we know as "Power Rangers" is actually the <a href="http://en.wikipedia.org/wiki/Kyouryuu_Sentai_Zyuranger">sixteenth entry</a> in the Super Sentai series, which didn't come about until 1992.