The shift from superhero parody to wrestling wasn't just Author Appeal, it has an in-universe justification. When Bibinba joined the Earth Defense Corps, she was so good at eliminating kaiju that there were none for Choujin to fight!
After the Justice Choujin's friendship is stolen by Sunshine and Ashuraman, Terryman becomes exceptionally mean-spirited. After all, he was a total, Only in It for the MoneyJerkass before his friendship with Kinnikuman reformed him!
The prelude to Kinnikuman Super Phoenix's Muscle Revenger having him repeatedly headbutt his opponent into the air might seem relatively innocous, until you remember that he was picked by the God of Intelligence for his brainpower alone, meaning he always uses his head and thinks strategically instead of attacking and counterattacking impulsively in a fight. In other words, the finishing move of a man who uses his head, quite literally starts out with him using his own head. Likewise, the compassionate, forgiving, Suguru's Muscle Spark has him bounce his opponent off of his chest, where his heart is located, as Suguru himself is an emotional and sentimental character who thinks with his heart.
The fact that Prince Kamehame was somehow unable to defeat Jessie Maivia, who ironically isn't that good outside of counter attacks might not make sense, unless you take in to consideration how he's a Glass Cannon. He can't afford to take big risks and goad him into going on the offensive like Suguru did in his fight with Jessie, because Maivia is much younger, and has better stamina and all around physical health in spite of Kamehame rigorously training himself even in his advanced age. Likewise, the fact that Suguru managed to beat him fairly easily also makes sense. Suguru is a young adult in his prime and is armed with Kamehame's techniques taught to him by the man himself.
Brockenman's poison gas breath might seem incongruous to the character at first. Then you remember that the Nazis used gas chambers to kill Jews in the Holocaust...
Soldierman, the original Kinnikuman Soldier chosen by the Evil God of Brutality is this, considering that the God of Brutality picked him in a world where there is not one, but three whole factions which have absolutely no issue with brutally murdering their opponents, which all have countless amounts of members who preform gruesome moves on their opponents without a second thought, and using highly cruel and unusual methods such as squeezing them to pieces, tearing them in half while they're alive and conscious, drilling a hole through their stomachs, slowly and painfully suffocating them, biting them to death, and crushing their bodies, as well as just simply tearing them to pieces through every method imaginable. Soldierman getting chosen by the literal God of Brutality himself implies that he somehow TOPS them all in terms of pure savagery and bloodlust. Thank the heavens that Ataru put him down and took his identity.
