Mix seasonings together and coat outside of meat all over. Add sliced onion to bottom of pot with half your can of soda on bottom. Place meat on top with rest of soda poured over the top of it.
Close lid and cook on low for 8-10 hours or until meat pulls apart with 2 forks easily.
Shred meat right in the pot and pour bbq sauce over the top. Use tongs to stir and coat every single piece well. If you need more sauce add to your liking, serve with buns.