Add chicken breast, sea salt, black pepper, and chili powder to slow cooker then pour barbecue sauce over top. Cover and cook on low for 6 to 8 hours or until chicken is cooked through and sauce is bubbly.
Remove chicken breasts from crock and shred with two forks. Place shredded chicken back in crock and stir to coat with sauce.
Serve on buns with sliced pickles and onions, if desired.