In a mixing bowl, combine olive oil, chili powder, cumin, garlic powder, onion powder, paprika, salt, and black pepper. Add the chicken breasts and coat well with the marinade. Let it sit for 10 minutes.
While the chicken is marinating, prepare the rice according to package instructions or in a rice cooker until fluffy.
In a large skillet over medium heat, add the marinated chicken and cook for about 6-7 minutes on each side, or until it is cooked through and no longer pink. Remove from the skillet and let it rest for a few minutes before slicing.
In the same skillet, add sliced bell pepper and onion. Sauté for about 5-7 minutes until they are tender and slightly caramelized.
Slice the cooked chicken into strips and return it to the skillet with the veggies. Mix everything together to combine.
To assemble each bowl, start with a base of brown rice, followed by black beans, corn, sautéed chicken and vegetables, diced tomatoes, and shredded cheese.
Top with avocado slices, fresh cilantro, and lime wedges. Serve with salsa or hot sauce on the side if desired.