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.
Anti-Climax: Parodied with the fight between Kenstar and Yusuke, consisting of them just trading barbs while getting ready to fight, until Kotobaru-san-sama asks them when they're going to just fight already.
"Mother... MOOOOTHEEEERR!!!! AAAAARRRRRRGGGGHHH!!!!" - cut to credits.
The Scrappy: Girl-chan seems to be an in-universe example (except for Swirly Glasses.)
Stupid Sacrifice: Parodied with Green Guy killing himself to defeat Maytag, a villain who didn't seem remotely dangerous and who pretty much anyone could probably have handled.
The Untwist: Yusuke being a Captain/Bushido Blaster is this both in and out-of-universe. His face is clearly seen in the wall of scribbles that's supposed to be the Bushido Blaster's portraits, and when he reveals himself, nobody's surprised except Green Guy (and Kenstar reacts more with mild annoyance.)
Villain Decay: While Galaticamaru never really did anything but smash walls and call the heroes puny, he is revealed to be very small himself and gets defeated by Yusuke.