What entity types are missing? A lot of them are only selectable when you apply them to a Hammer mesh. An easy way is to create a mesh with materials/tools/toolsnodraw.vmat on it, and make it a prop_rotatitng entity. Then parent whatever you want to rotate to the mesh.

Well I wasn't able to find prop_rotating as an entity, only func_rotating, which I couldn't get to work. I was able to locate the phys_motor point entity, which I'm trying to make work at the moment, but so far it just makes the tied object disappear when I build the world.

I think what I took for missing "entities" was stuff like func_physbox which I think is outdated.

Ah sorry, I meant func_rotating. The only things I changed with it, was adding a name, and setting the Start ON and Not Solid spawnflags.

Thank you, got func_rotating working. I think it wasn't working before because I had it on mesh mode rather than object mode when trying to edit properties.