The electric seaweed level in Ninja Turtles was every bit as hard as the jetski level of Battletoads. I remember the Earthworm Jim underwater level with the glass sub being incredibly frustrating too, but beatable.
I know I beat Earthworm Jim, think I beat Ninja Turtles, don't think I ever beat Battletoads.
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"The Rich are there to take all of the money & pay none of the taxes, the middle class is there to do all the work and pay all the taxes, and the poor are there to scare the crap out of the middle class." -George Carlin