I want it so that instead of HMs, you learn from the gyms you face, as well as the gym leader's guidance, how to overcome the HM content.
>Second Gym teaches you how to cut down obstacles in your path, allowing you to cut down trees upon defeating the gym leader
>Fourth gym teaches you how to overcome insurmountable odds, allowing your pokemon to push large boulders for you when you beat the gym leader
>Fifth gym teaches you balance so you don't fall off when surfing. I mean, what else works here?
>Seventh gym teaches you something about revisiting the past to better yourself for the future, or something like that. You are allowed to fly on pokemon with this badge.
You still get the HMs, and they still count as HMs, but they are not necessary for travel as your pokemon learn how to apply these effects in the overworld without knowing a move.
Think about it; Scyther doesn't naturally learn Cut, and it has giant scythe arms. It's not extinct, so it must do SOMETHING with those sharp claws, right? There's also water pokemon and surfing, and strong pokemon and Strength. Imagine a Machoke that couldn't move a boulder, or a Seaking that doesn't know how to swim. How sad is that?