The NES defined a genre called "NES Hard". These refer to the steep difficulty settings that a lot of these games had, even on the easier difficulty settings.
Battletoads was released by Rare/Tradewest in 1991. Now, by this point, Turtlemania was in full swing. So everyone was eager to cash in on the success of Ninja Turtles and make their own animal themed superheroes. This is where Rare changed things up. They made a distinctively NES Hard arcade brawler.
This two player brawler would really fit into that NES Hard category. It's brutal, unforgiving and will eat the novices for breakfast. Gamers today know the painful sting of running out of continues on Level 2 and the Turbo Tunnel.