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.
Ass Pull / Deus ex Machina: How some of the characters won their matches, such as Sanae finding the right opening or Mokou and Kaguya suddenly getting stronger in the middle of their match with Komachi and Shikieiki. Though Sanae has gotten better in this regard, winning through more skill/determination than writer's saving grace.
Base Breaker: The Hourai vs Pyramid Volcano battle was a massive readership divisor. There are those who accept the outcome because Mokou chose Keine's well-being over the victory, those who hate Kaguya's guts for all the underhanded tactics she pulled from her first encounter with Mokou until now and think she deserved to get her ass kicked and didn't deserve the win, those who agree with Mokou but still despise Kaguya for the aforementioned reasons and those who dropped the series entirely as a result. And although team Pyramid Volcano managed to come out of the Heel fame they got because of Kaguya, that Kaguya still managed to come up on top of everything without any sort of comeuppance for her underhanded tactics and that if not for said tactics, Pyramid Volcano would have achieved victory way before the climax did not help matters at all.
Crowning Moment of Awesome: Kaguya and Mokou, together, Pull out a chain of, in that order: Neo Kinniku Buster, Big Bang Edge and Kinniku Driver on Komachi, who was constantly walking over them.
Ensemble Dark Horse: Tenshi and Okuu with support from the underground youkai. With the efforts made by Parsee, Yuugi, Orin, and Yamame leading into the duo becoming an effective yet fun to watch team in dealing with tough foes (unlike Red 75%) in clean ways, english fans are rallying behind them. Their off ring interactions reveal traces of Fun Personified, moments of heartwarming, and Tenshi's intent to oppose the sneakier elements of the tournament, such as how the Immortals and Organizers do things.
Growing the Beard: The 4koma was never exactly bad, but it started out as a silly, light-hearted parody of Kinnikuman. Somewhere around the first few fights, it lost the parody part and became just a straight homage... and then during Hourai vs Pyramid Volcano it bid farewell to the light-hearted part.
Never Live It Down: No matter how much of a serious referee she is later in the series, no one will ever let Aya's biased refereeing in Hourai's favour against Pyramid Volcano be forgotten.
Villain with Good Publicity: Kaguya (and later Mokou) doing flashy shows and bribery to build up good publicity enabling them to use Heel tactics and still come off as Faces to the fans. (the in-story fans, that is; among the readers, Kaguya tends to gather X-Pac Heat.)
Kanako and Yuyuko showed signs of this when they more or less get away with their attempt to silence Yamame and Parsee for merely trying to persuade them to let Okuu into the tournament (She was basically banned for doing something Yukari, another organizer put her up to doing). The worse that happened to Kanako was Yuugi gave her a parting punch to the face. However unlike Yukari, Kanako hasn't done anything shady at all since then.
Yukari herself for different reasons: Intentionally snubbing Tenshi and the underground dwellers, prodding Okuu to attack the assembled normal contestants, which wound up failing (only Koakuma and the Akis were affected). She then punished Okuu for it. And there are signs that she's favoring Reimu (most obvious of which was adding a cash prize just to get her alone to enter).
This means that Heaven Sky (Okuu and Tenshi) are her unfavorites and so far they have overcome Sakuya/Suika (with Sakuya getting some special training from Yukari just to deal with Yuugi, which improved her 'time barrier' to damage reflecting levels).