Power Scaling in One Piece is well done, and operates around a system of checks and balances.
What determines strength:
Race (Fishman are 10x stronger than humans normally)
Gender (female pirates are generally weaker, it was Oda's decision, not mine, please don't get angry at me)
Ambition (Crocodile was much more powerful than Luffy, yet lost due to Luffy's superior Will)
Intelligence (Luffy is a genius/jester of a fighter)
Training (Luffy and Zoro often get stronger in tough fights and Zoro trains all the time)
Special Abilities (Devil Fruits, stuff like Arlong's teeth coming out, Ms. Golden Week's Color Trap)
Haki
This allows a nice series of counters.
Fishmen are stronger than humans, but humans can still beat them if they try
Women pirates are usually weaker, but can be strong, like Robin, Carrot, Smoothie, and Big Mom
Paremecia Fruits are hit or miss, but there are amazing top end fruits (Gura Gura, Nora Nora, Ope Ope)
Zoan take the most time to master and give the least amount of base benefits, but can become monstrously strong over time and through Awakening
Logia are incredibly powerful from the get go, but many never reach their peak with Logia, because they rely on them too much and don't develop their Haki and other skills enough (Enel, Caribou, Ace to some extent), and can get bodied by Haki
Haki is powerful, but Haki isn't enough to overcome clear differences in power, so it's not broken. IE, if Sanji uses Haki on Big Mom, and Big Mom isn't using Haki, Big Mom's fist will still win most times.
Haki counters Devil Fruits, but doesn't completely negate them
Devil Fruit users are weak to water, so it's hard for them to fight on the open-seas without risking death/being a burden. Big Mom is much more powerful than Law and Kid, but, she's also way dumber. Both times they seriously pushed her, they used their abilities to force her into the air so she was unable to maneuver herself. They knew they couldn't straight up kill her in a fight, so they focused on using the forces of gravity, and the force of nature know as the ocean, to fight her.
One Piece isn't Pokemon. Just because Crocodile has much higher stats, and a much better grasp on his Fruit, it doesn't mean he automatically wins over Luffy. Most powerscalers just want their favorite characters to be powerful, and want to ignore any nuance that goes into a fight. Hell, I've pushed ZKK heavily, and I think Jinbei has a case for being stronger than current Zoro.
But Jinbei will never get ranked anywhere near Zoro, because Jinbei doesn't have many fans, and Zoro fans are fucking crazy (source: am Zoro fan).
