Super Mario Land 2: 6 Golden Coins (Gameboy)
I recently replayed this. For some reason now, like back in the day, I can breeze through the entire game but I just can't get past Wario's stage!
@ohnoanotherputz I could as a kid too. Last time I played this on an emulator I got destroyed on the last stage but I did it yesterday and breezed through. The key is to have kill counter on 99 so you get a star after killing the first of those flying faces. They were always the hardest bit.