One Piece : Winged Dragons of the Beast Pirates

he fought and badly injured moria who was said to be as strong as all-star of beast pirate, and killed all his crew members [some of them knew haki] at the age of 5 ,then defeated hyogoro who had learned emission at the age of 8 by this time he already had haki, yet even after so many years when he became a teenager he's still at this level, his haki didnt progress and hasnt even learnt observation haki, he's devil fruit is whats carrying him all this time, kaido said he's even stronger than himself and bigmom at same age yet he cant even defeat marco [more than 10 years before canon] who is only high vice admiral level rn, he's already reaching luffy's age after the timeskip yet is way weaker, the author made him too strong in the beginning so now he is doing damage control, ps: he's haki is said to be weaker than squard despite unlocking it at young age and being brutally trained by kaido from the age of 3. im not saying the mc has to be overly OP but if u make him OP from the start than stick to it, nerfing him leaves a bad taste. if you dont want him to be OP than do weak to strong instead

Everything was good until he started adding more wife. Boa and Viola were unnecessary. Especially Boa, she destroyed the dynamics between the mc and yamato