Place chicken in a 4-qt. slow cooker; add black beans, pepper and onion. In a small bowl, mix picante sauce, garlic powder and cumin; pour over top. Cook, covered, on low until chicken is tender, 4-5 hours., Remove chicken and cool slightly. Shred meat with 2 forks and return to slow cooker; heat through. Serve with tortillas, cheese and toppings of your choice.