Nightmare Fuel / JoJo's Bizarre Adventure: All Star Battle

  • Doppio's transformation to Diavolo, at least in PV 5, is quite unsettling. We see Doppio pop up and be his usual self, when suddenly his eyes turn uncharacteristically sharp and aggressive, and his voice drops several octaves. For the brief seconds we see Diavolo!Doppio, the whole thing comes off like he's possessed. Then he steps through the panel divider, apparently pulling off his shirt, and Diavolo comes out the other side. (It's based on manga panels where removing his shirt triggered the change, but you can't tell from the game's cutaway.)
  • Fugo's GHA has him infect his foe with the Purple Haze virus, which is known for inflicting a swift and painful death to its victims. Enjoy the screams of pain and anguish. The only reason the game's isn't rated M is because the screen turns black-and-white for a moment during the attack.
  • Funny Valentine's GHA is fairly unsettling: he transports himself and his opponent to an alternate dimension, next to said dimension's versions of themselves. Valentine's safe, thanks to his stand, but his opponent ends up getting fused with his alternate self and splitting apart into Menger sponges. The game's graphics engine uses tricks with the color, similar to with Fugo's GHA to compensate for the fact that what's happening to their bodies is really gnarly.
http://tvtropes.org/pmwiki/pmwiki.php/NightmareFuel/JoJosBizarreAdventureAllStarBattle