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.
Gash has horns on his head when Kiyomaro is forced to wash him after a battle. Other Mamonos have horns, yet it is never brought up ever again.
The demon Momon was known to let out "kikiki" like sounds, akin to a monkey, but suddenly begins talking multiple volumes later. No one questions it.
One of the manga chapters is completely dedicated to a weird dream Kiyomaro had. It involved the reappearance of many characters (like Kiddo, D'artagnan and Leila), Sunbeam dressed as a fairy, "Manly Brago" teaching how do do "Silly Juggling" and many characters slapping Kiyo silly with various items. Apparently Kiyo loses his answer-talking ability for a while after having it, but the dream itself is never mentioned again.
It was implied that Kiyo was overusing the Answer-Talker Ability and the dream was a manifestation of the overuse as well as the stress from the events.
Complete Monster: Of all the evil demon children, Zofis was easily the most vile. A total sadist and an egotist, he horribly Mind Raped both humans and fellow mamodo, for practical reasons and For the Evulz, and enjoyed nothing more than the suffering of others. He also kept an army of 100 year old demons in line by creating the illusion of turning them back into stone tablets, thus being able to control them using their fear. He despised Brago and dreaded his power so much that he attemted to take his life rather than simply burn his spellbook and send him back to the Demon World. Most notably, he warped the heart and mind of Sherry's best friend Koko and made her do anything he wanted her to do, specifically if it hurt Sherry in any way (Koko nearly even jumped to a fiery, burning death because of him). His final threat was to not erase Koko's memory of her time as his partner so that she'd always suffer from the guilt and stay broken as a result, a threat that thankfully became empty when Brago forced the Dirty Coward into a Villainous Breakdown that left him broken.
Crazy Awesome: The entire series and almost every attack in it, particularly Kanchome's. Almost every single minor character has some kind of crazy attack, too.
And a good example of this? Sunbeam spent ten months in Africa. Immediately after he comes back...well...rock and roll!
Ensemble Darkhorse: Victoreem, for... well everything. On top of his generally memetic theme, that utterly batshit song, and general ham, he's voiced by none other then Norio Wakamoto. His popularity is lampshaded repeatedly in omakes and the ending of the manga.
Growing the Beard: In the case of the anime, it takes a long while for the series to really take off and become something epic...until episodes 44 and 45, which features a brutal battle that Kiyo and Zatch flat-out lose. Shortly afterwards we're introduced to the stone tablets of 1000 year old mamodo in episode 48, and it just keeps going from there!
Macekre: For the most part avoided except for one infamous element; the radioactive guns.note The localization did a good job balancing the violence in the shows to appease the censors. The one pesky element they could not work around were all the guns, so instead of making them invisible like in Yu-Gi-Oh!, the localization team gave them a light green glow.
Only the Author Can Save Them Now: Against Clear Note. The rules of the tournament established throughout the story had to be completely broken to give the main characters a shot at victory.
Villain Sue: Depending on who you ask, Clear Note is either a Villain Sue or an intentionally over-the-top parody of Villain Sues. He's a BishōnenGeneric Doomsday VillainDiabolus Ex Nihilo who makes his completely unforeshadowed entrance by beating Brago (until then the strongest character) half to death, defeats the Supporting Leader despite the fact that said leader's skin is explicitly resistant to his powers, comes back stronger every time you beat him up, is a Hero Killer (including one kill from thousands of miles away while critically wounded), and ultimately required what seemed suspiciously like an Ass Pull (it was foreshadowed... over three hundred chapters prior) to finally defeat. Whether all of this is annoying or darkly hilarious, again, depends on who you ask.
Wangst: Gash/Zatch can go a little overboard with his crying sometimes....