Yeah, I though it wasn't common in Emerald.  But iirc, inheritance in Emerald is a lot different from the others in the same gen, so this could be different too.
One more thing: I checked the new version of RNGReporter's 3rd gen features, and there's something about Method H for stationaries.  I always though stationaries used standard Method 1.  I recall OmegaDonut claiming he has a Method 2 Mewtwo.  What's that about?