Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

How do the Ringwraiths compare to other villains in Lord of the Rings?

 In J.R.R. Tolkien's Middle-earth fantasy universe, the Ringwraiths, also known as the Nazgûl, are powerful and malevolent beings who serve as the primary antagonists of the story. The Ringwraiths are nine immortal beings who were once great kings and lords, but who have been corrupted and enslaved by the power of the One Ring, a magical and malevolent object that has the ability to dominate and enslave the inhabitants of Middle-earth.

The Ringwraiths are powerful and formidable villains who are feared and hated throughout Middle-earth. They are able to sense the presence of the One Ring and are able to track it wherever it goes, making them a formidable enemy for the protagonists of the story. They are also nearly indestructible, as they are immortal and can only be killed by destroying the One Ring itself.

In comparison to other villains in The Lord of the Rings, the Ringwraiths are unique in that they are not motivated by personal ambition or greed, but rather by their loyalty to Sauron, the main antagonist of the story, who created the One Ring and seeks to use it to conquer Middle-earth. They are also distinctive in that they are not physical beings, but rather spirits that have been bound to the physical world by the power of the One Ring.

Overall, the Ringwraiths are powerful and malevolent villains who pose a significant threat to the protagonists of The Lord of the Rings and are unique in their loyalty to Sauron and their bound spirits.