These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Designated Hero: In the manga. See that guy who rapes a girl over and over again? See him treat everyone around him like dirt? See him suddenly go back to normal because "It wasn't really him" and accept no responsibility for any of his actions? That's our hero. Averted in the anime, where Masato is horrified by Masaki's actions and at one point asks Miku to kill him to prevent Masaki from taking over.
Game Breaker: Every time it appears in Super Robot Wars, thanks to its combination of a barrier, DCS evasion, and regeneration. Get its Will to 130, drop it between foes and watch the fireworks.
Though as some have pointed out, giving every villain a flaw that allows you to manipulate and control them and thus keep the battle always in your favor, is writing-wise no different from just putting a bomb in the cockpit with your hand on the trigger. It's essentially letting the protagonist cheat.