You know I had given the benefit of the doubt that these pokemon did evnetually get more moves to use them but...wow, no, you're right. Even as of gen 8....-Kantonian Golem, Rhydon, Kantonian Marowak, and Aerodactyl getting nothing of to use with Rock Head outside of Double-Edge, which is exclusive to Gen III(Also Rhydon and Aerodactyl get Take Down, but no-one cares about that)
-On a similar note, The Rhyhorn line Getting Reckless as their Hidden Ability but get nothing but Take Down without the help of the Gen I VC games, and even with them all it adds is Double-Edge and Submission. Getting a HA Rhyhorn/don/perior in Gens V-VIII is completely pointless
Why are they so skiddish about giving Head Smash to these Pokemon? Honestly its a miracle Aggron got it. Golem, Rhydon/Rhyperior and Marowak in particular are all fairly slow Pokemon that wouldnt tear the meta apart or anything.
At the very least give them Double Edge. Even Basculin got Double Edge. And USUM gifted it Head Smash!
e: You know while looking through the recoil moves, I'm surprised at how few there are in the series.