Step 1Combine 5 cups of water, the California, ancho, guajillo and cascabel chiles, the chile de arbol and the bay leaf in a large pot and bring to a boil. Boil for 5 minutes. Remove from heat and let stand until softened, about 5 minutes. Drain the chiles, discard the bay leaf and remove and discard the stems and seeds of the chiles.
Step 2Place the softened chiles in a food processor with the orange and pineapple juices, vinegar, cinnamon, sea salt, garlic, salt, pepper, garlic salt, oregano, achiote paste and half the onion. Puree until smooth.
Step 3Pour the marinade into a large resealable plastic bag, add the meat and toss to coat. Refrigerate 24 hours.
Step 4Heat the oven to 350 degrees. Place half the pineapple in an even layer in the bottom of a roasting pan. Place the pork on top, followed by the remaining pineapple and the remaining sliced onion. Cover with foil and roast until meat breaks apart with a fork, about 2 to 2 1/2 hours. Remove the meat from the pan, discard the pineapple and set aside the pan juices.
Step 5Put the meat on a rack in a baking pan, baste it with the pan juices and place under the broiler to crisp the edges of the meat, about 3 minutes. Turn and cook for a few more minutes.
Step 6Remove the meat from the oven and let stand until cool enough to handle, then, with a fork, shred and pull it apart and place on a serving platter. Spoon pan juices over to moisten. Serve with corn tortillas and condiments, allowing everyone to make their own tacos.