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.
Americans Hate Tingle: Ironically, Terryman is one of these to the American fanbase (or possibly a Base Breaker rather than an outright Scrappy) while in Japan, he's a regular Ensemble Darkhorse. While he's the only Expy in the series to use the same moves as who he's based off of (Terry Funk), a lot of Western fans criticize him for being weak and boring because of this same fact because he's in a series where other people pull off some insanely awesome wrestling moves. Terryman's rather lackluster Win/Loss record does not really help his case with the Western fans either.
Angst? What Angst?: Bibinba doesn't seem to mind the fact that falling in love with Kinnikuman means that she's falling in love with someone from the clan that killed her mother.
Kinnikuman never really blamed his father for being left on Earth. That didn't stop them from constantly butting heads over everything, though.
Ear Worm: A lot of the image songs are pretty catchy, the best examples being Brocken Jr. and Kendaman's.
Some of the theme songs, too. Burning Kinnikuman, in particular.
Ensemble Darkhorse: Ramenman. Initially introduced in order to give Kinnikuman a brutal heel wrestler to get him psyched up for his match against Robin Mask, he was so popular that he was elevated to secondary character status. After that, his popularity skyrocketed to the point where he even got his own Spin-Off, Tatakae! Ramenman.
The same goes for Buffaloman; At the beginning of the seven devils arc (where he was introduced), they were initially setting up Black Hole to be the arc big bad, but Buffaloman proved to be so popular that he got upgraded to the Big Bad while Black Hole was reduced to a mere lackey.
Sunshine and Ashuraman are quite popular among fans as well. The fact that they were Affably Evil and then eventually make a Heel-Face Turn helps too.
To a far lesser extent than any of these, Leopoldon from Team Big Body, who is far more popular than the rest of the team including Big Body himself despite being one of the victims of The Worf Effect when sent up against Mammothman.
Likewise, Wolfman/Rikishiman is a lot more popular than you would think for someone who pretty much exists for the use of The Worf Effect.
Terryman is this in Japan. In one popularity contest he actually came first.
Robin Mask is much loved by fans, particularly Americans and of course, his native country of England.
Brocken Jr's has a pretty good fan-base.
Neptuneman was an intimidating villain who not only gets his own movie, but also gets a Heel-Face Turn
Akuma Shogun, the fact that he got his own movie says a lot.
Warsman has quite the following as well.
Among those whose primary exposure to the franchise is by collecting the M.U.S.C.L.E. figures, Satan Cross. This comes mainly from the fact that he was one of the few figures that was available in packs but was not pictured on the official checklist poster, making many people believe that he was incredibly rare (in reality, he was no more hard-to-find than most other figures).
The M.U.S.C.L.E. line also had Sneagator's claw form, which quickly became the most popular figure in the series, for reasons less related to any significance or character traits and more because it's a giant warty hand with a face on it.
Epileptic Trees: Fans speculate that Brocken is a personification of post World War II Germany, continuing to wear his father's uniform thus not abandoning his heritage yet refusing to be a heel like his father (who was a Grade A Nazi). They also say that Brocken Jr was a character that might have been created to give an image of a reinvindicated Germany.
"Funny Aneurysm" Moment: All the jokes about the 1980 Moscow Olympics are somewhat less funny considering that Japan (along with a lot of other nations) decided to boycott the games.
Kinnikuman. He may be a Jerk Ass (more of a Jerk with a Heart of Gold), a letch and a coward, but it's hard to be nice to people when you're a laughingstock among superheroes and get no respect from anyone, even when you do actually help to save the day.
Warsman. He was a brutal, killing machine when he was first introduced, but he reveals that in the past, he was tormented and rejected everywhere he went as a child because of his hideous appearance, and only took to the ring so he'd be allowed to fight back. Even worse, his mechanical body malfunctions after 30 minutes of fighting, meaning that he literally cannot push himself beyond his limits. This makes it all the sweeter whenever he manages to turn a fight around, and earned him quite a few fans.
Buffaloman. In his introduction arc, he was a Blood Knight who only cared about power. Flashbacks in the arc showed that before his Deal with the Devil, he believed in fair fights and friendship in the ring, which displays of it from Kinnikuman and company made him deeply ashamed at his obsession for power and help him to Heel-Face Turn. It gets worse in the Throne arc, when it's revealed that he's actually the Last of His Kind of a Proud Warrior Race that destroyed itself because they did nothing but fight among each other and ends up stopping the Five Evil Choujin Gods from killing Kinnikuman Soldier using foul play because he doesn't want the same thing to happen to Kinnikuman's family.
Kinnikuman Super Phoenix grew up poor and alone, hoping that he could prove himself to be the heir and be taken away from his misery. His jealousy only increased when Kinnikuman was revealed as the prince of planet Kinniku, as Super Phoenix saw Suguru as an idiot who got money and recognition without working for them, while Super Phoenix was intelligent and had to struggle to survive. He gets better after Kinnikuman defeats him, leading to a Crowning Moment of Heartwarming when Suguru considers him as a friend and family member and comes to his aid against the five evil Choujin by preventing them from killing him.
Kinnikuman Mariposa. He was a thief and was the one who stole the Anolao Flame from the Robin family, but he literally had no other choice as his family was dirt poor and he would have probably died of starvation if he didn't steal to provide for himself.
Kinnikuman Zebra. He worked hard as a farmer to earn money to buy his way into the Choujin Society. His only friend during this period of his life was his pet zebra, Zebra Kid. After a really sad situation caused Zebra to kill his friend, his Start of Darkness began, as he immediately discards any concept that was foreign to the concept of money, ultimately paying his teammates to fight for him in the throne battle. His match against Kinnikuman ended as one of the biggest TearJerkers of the series.
Moral Event Horizon: Planetman crosses it with perverse glee in his match against Kinnikuman. He first skirts the line when he imprints the entire Earth on Kinnikuman and starts stabbing all the countries on Kinnikuman's body which not only hurts Kinnikuman, but the Choujin that came from the continent stabbed, breaking their life-preserving bubbles. Then he uses his secret technique, Planet Face to imprint the faces of Kinnikuman's friends and loved ones (including Bibinba and his own mother ) on his planets so Kinnikuman can't attack him without hurting them, crossing the line and managing to anger Kinnikuman.
Super Phoenix starts off being dangerously close to the horizon, but he pretty much crossed it when he says that Ataru deserved to die for running away from his parents.
Older Than They Think: There are many who attribute the invention of the Kinniku/Muscle Buster to either Samoa Joe, the Smackdown Vs. Raw series, or King from Tekken, not realizing that the series predates all of them by decades.
Signature Scene: The Kinniku Buster. If you read a lot of shonen manga, chances are that you've seen at least one Shout-Out to it.
Values Dissonance - The video for Megumi No Hito, which at first appears offensive, until you learn who the video is a homage to note Rats & Star, the ones who are singing the song. Keep in mind that Rats & Star did blackface in order pay tribute to the African-American do-wop bands from yesteryear that they had so much respect for..
Viewer Gender Confusion: Sure, it's common for female seiyuu to voice young male characters, but Meat's voice in the anime doesn't even give a slight indication that he's a boy.
Villain Sue: Dirty Baron in the last filler arc in the original anime. He can counter all of Kinnikuman's moves, he has variations of the other main characters' techniques, he's Buffaloman's blood brother, and he's only defeated by a Deus ex Machina.
What an Idiot: Mayumi, the current king of Planet Kinniku, is usually known for making situations worse whenever he tries to fix them, but there was one point in the Throne Arc where he royally fucked up - when the revelation that one of the possible successors to the throne is actually your eldest son that was banished from the family could cause a total disaster in the world of Choujin, the last thing that you should do is hold the one book that could prove it true in a place where it could be stolen.
The Woobie: Nachurigon. He was classified as a "loser monster", which lead to him being picked on by other monsters and even the humans that he's supposed to be attacking.
Woolseyism: "Kinniku" translates to "muscle" in English, but there's already a character whose last name is "Muscle" - Chairman Harabote Muscle, who isn't related to the family. In the English translation of the manga, his name is changed to Vance McMadd, which both avoids potential confusion and is a parody of WWE CEO Vince McMahon, which fits with the series' tradition of using parodies of well-known wrestling personalities.