Place pork shoulder in your slow cooker. In a bowl, whisk together pineapple juice, barbecue sauce, soy sauce, brown sugar, garlic powder, onion powder, and black pepper. Pour over the pork.
Cover and cook on LOW for 6 hours (or HIGH for 4 hours), until the pork is fork-tender and shreds easily.
Remove pork, shred with two forks, and return to the juices. Stir to coat.
Slaw (Optional): Toss coleslaw mix with mayonnaise in a small bowl.
Pile pulled pork onto slider buns. Top with slaw if you like. Drizzle with extra barbecue sauce.