Abstract: Drilling in interbedded soft-hard formations often leads to issues such as unstable bit performance and short service life. To address this, research was conducted on bit selection and formation adaptability. Eight non-conventional cutting tooth models were developed, and stress variations during the interaction between teeth and formations in the Shaximiao–Xujiahe–Leikoupo interbedded soft-hard formations of the Sichuan Basin were analyzed using finite element simulations. The study reveals that penetration stress is primarily governed by tooth geometry. The optimal geometries are the new ridge tooth, ridge tooth, and triangular prism tooth, while the cylindrical tooth performs the worst. Penetration stress in hard-soft formation sequences exceeds that in soft-hard sequences, with higher values observed in hard formations. Stress fluctuations during continuous cutting are mainly controlled by the planar symmetry and 3D structure of non-conventional teeth. In soft-hard sequences, asymmetric geometries like triangular prism and pentagonal teeth exhibit greater stress fluctuations in soft formations. In hard-soft sequences, elongated conical teeth generate higher stress fluctuations in hard formations. Considering both penetration capability and cutting stability, the new ridge tooth is the optimal choice, while ridge and triangular prism teeth are viable alternatives in hard-soft sequences. The findings were validated by field drilling data and will guide future optimization of PDC bit designs with non-conventional teeth.