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.

What are some 'rules' to live by that are specific to your region's folklore?

 there are many different cultural traditions and practices around the world that have shaped the values and beliefs of different communities. Some general "rules" or guiding principles that are common to many cultures and societies include:

Treat others with respect and kindness.

Do unto others as you would have them do unto you.

Be honest and trustworthy.

Work hard and be responsible.

Help those in need.

Be grateful for what you have.

Respect the traditions and customs of your community.

Appreciate and care for the environment.

These are just a few examples, and the specific rules and principles that are considered important may vary from one culture to another. It is always a good idea to try to understand and respect the traditions and values of the communities in which you live and interact.