Why isn't Stone Edge a possible egg move for Dugtrio?

Question

I'm completely new to breading, so my apologies in advance for not understanding this.

Rhyhorn learns Stone Edge at level 52, and is in both the Field and Monster egg groups.
Since Diglett (and Dugtrio) are also in the Field egg group, why can't Stone Edge be passed down?

I assume that this move can't be passed down since it is not in the list of egg moves on the Dugtrio page.

Answer 1

All HM/TM moves that are compatible with the offspring will be inherited if the father Pokemon knows those moves.

However, while Dugtrio can learn Stone Edge via TM, Diglett can't, and since you will always hatch the Pokemon that's the lowest of its evolutionary chain (with the exception of some baby Pokemon), Stone Edge is therefore not a bred move for Dugtrio.

Also, the egg moves list only list moves that can only be obtained via breeding (rarely you'll see TM moves on the lists, but that's usually by accident).

Bulbapedia - Egg Moves

Comments

I understand now. Thanks for clearing that up. I just assumed Diglett would be able to learn the same TM's as Dugtrio.