[Guyver Spawn]

It depends on the show. I feel like the older Sentai shows did had some more serious subject matter compare to PR. Zyuranger may have been a dumb kids show in Japan, but it still had some serious themes like Death which MMPR never really did.

Also in the 80's, 90's and the early 2000's, any Japanese kid show that was dubbed or adapted in the US, had to do changes to make it more American TV friendly for the Kids Network. Like with Voltron, Robotech, Sailor Moon, Dragon Ball Z and several others. TV shows these days in the US are a bit less strict compare to what it was 15-20 years ago if you ask me.