Place chicken at the bottom of slow cooker. Cover in garlic and season with salt and pepper.
Add onion and peppers on top and around chicken.
Add BBQ sauce, chili powder, onion powder and paprika and spread sauce to cover chicken.
Close and heat on low for 6-8 hours or high for 4-6 hours depending on your crock pot.
When chicken is cooked through, using two forks, shred chicken and stir well to allow it to absorb the sauce.
Stir in corn starch to thicken about 20-30 minutes before serving.