Character Discussion Most wasted character in One Piece ?

It's raw and maybe it's premature, but I'm underwhelmed by Vegapunk to the point of being salty.

He was supposed to be the genius grand line scientist who could do all these amazing things with devil fruits, feed them to objects, extract their powers from one user (kizaru) and give them to another (kuma), and most importantly, explain what they truly are. Instead, all we got was some feel good nonsense about people's dreams.

He was supposed to be able to use ancient technology in a way no one else a way he did, but his work got hijacked by the gorosei, and he couldn't do anything about it.

Overall, he's been incredibly "street stupid" especially now that his contingency plan of the ancient robot safeguarding the broadcast den-den mushi failed as well. He let himself get betrayed by his own creation, apparently knew it was happening, and took inadequate measures to prevent the impact.

And, unless there's a curveball next chapter, he was hyped to potentially reveal something new about the void century, instead he offered no materially new information to the reader.

Name dropped in an SBS I don't even know how long ago, maybe 20 years, at least 15...and this is what we get. Even his death scene was pitiful and frankly disrespectful. So much so that I'm still not 100% bought into him actually being gone.

On the topic of Big Mom, I sincerely feel sorry for you folks that are big fans of her. Both given that she was a woman and her downfall arc being the penultimate one of the series, it was mostly written in the stars that she was going to get done dirty by Oda. Her and Kaido were meant to be the last "strong" characters to go down before we entered the endgame. That was pretty much their only purpose, to demonstrate that Luffy was ready for the endgame. The worst part about her nerfed personality to me is how its mislead most of the fanbase to view her as a dumb or childish character, and diminish the edge off of her evilness. Whereas when she was lucid, she was cruel and calculated as the likes of Doffy and Crocodile, if not more. I don't put her strength level as high as you, but as a leader, she was truly everything you'd expect a pirate with the title of emperor to be.
Honestly I didn't feel any hype when we finally saw Vegapunk and that he met Luffy. I had become so jaded and cynical about One Piece at that moment, after the disaster of the Yonko saga, that his appearance couldn't give me back any excitement for OP, and I was certain that after what he did to BM, Kaido and their crews and Wano, Oda wouldn't deliver with him either.

Unfortunately I was right.
There’s a lot of wasted characters. However number 1 has to be Dragon, I get that he will have some panel time before the end but the fact that he’s just been sitting around for 1100 chapters is the definition of a wasted character. The Reverie should have been the arc in which he made his grand entrance, but instead Sabo hogged all the action.

I would say Kid also was wasted as a rival albeit he’s not as important to the plot. But for all the praise Oda gets for his worldbuilding and with over a 1000 characters in the series, you’d think Oda would use Kid as a rival who challenges Luffy in the PK race via his own methods and his own ideals against Luffy’s methods and ideals. Not only do we not get that but Kid is instead turned into a tsundere who talks the talk but can’t walk the walk. And this is a symptom of Luffy being a trash MC, since Water 7 and Marineford he hasn’t had any moments where his character was challenged. Oda attempted to do that in WCI but it flopped.
He took the “fun” way too far. Crocodile, lucci and Doflamingo weren’t goofballs. Big mom’s background and motivations weren’t goofy, fundamentally she was a cunning, ruthless dictator who got dumbed down temporarily to allow the main character to progress in the story. The goofy moments were worse than pointless, they ruined her characterization.
I can agree that the goofy moments were worse than pointless but it was very clear from the onset of her debut and WCI theme that she was supposed to be this cheerful and bright but also very dark and ruthless dictator, different from the Yonko rest in that they continue to be edgy and too tryhard at times. Why do you think we got that 1-page Kaido flashback or Shanks keeps his stoic cool demeanor with as much emotion as a wooden plank? Oda used her as a way to relax the seriousness of the plot at times generated by these characters and kept her as a wildcard for it.

She was the Luffy of the big villains and now that role has fallen onto multiple characters like York, Buggy, etc.