For any recent seasons like King Ohger or Don Brothers, you kinda only have one option. As far as I know Toei hasnt provided any means of watching their most recent seasons outside Japan, so youd have to rely on fansubs. Various seasons (mainly older ones like Zyuranger or Jetman) have been officially put on streaming services like Pluto or Tubi or on Blu-rays, so you have those options.
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