[@SleepingSilence]

As I said before, knowledge is an important part of trying to learn a new technique. But [i]knowing[/i] something is possible is way different from knowing how to do it. Technically Trevor could skip Ember and try to go straight into Fire Blast. Obviously at his level it would take him forever; by the time he learns Fire Black as a charmander one of y’all is probally going to evolve. Additionally a lot of these moves serve as the building blocks to more advanced moves: ember obviously leads to various Fire breath type attacks, but smokescreen could also lead to learning useful moves like haze or smog. And while you might think smog isn’t one of Chamander’s move, it’s possible thanks to the fact he can learn smokescreen.

Another barrier to learning moves are different elemental attacks. For example, how would Lance know how to do a Slash, Night Slash, and Dragon Claw when they’re all basically just him slashing someone? Different elemental abilities but simple slashing in the air calling your attacks won’t let you learn or train that specific move. Hence the need for tutors who can explain the specific (which I’ll make up if/when it’s needed). 

As for training moves themselves, frankly all of them work best if you actually use them on someone. Sure you can just go through the motions and free form practice them, but it’s not as effective as using them on an actual Pokémon. If you’re the type who wants to grow strong faster you best bet is to go after other Pokémon and fighting them. With all the risks that implies. Or finding a good teacher. With all the risks that implies.