Long answer- projectiles with relatively short length and shallow angle boat tails or no boat tail at all have better stability throughout their flight, particularly transonic. Finer meplat dia helps also as does a better transverse to axial inertia ratio.
I agree with Gropers assessment of what geometric and mass properties are good for a bullet's transonic stability.
A recent example of such a bullet is the Berger 175 Tactical OTM which I designed specifically for transonic stability:
Increasing twist rate can help a little, but the biggest outside influence is atmospherics. Many bullets that are not transonic stable at sea level are so at 3000+ feet elevation.