Sorry, follow by my last question, i've checked
https://bulbapedia.bulbagarden.net/wiki/Marowak_(Pokémon)
And based on my understanding,
1. Marowak-Alolan is a gen 7 poke, there's no gen 6 TM set to follow, so "it cannot learn TM-Dig on gen 6" is not true
2. When it first released on gen 7, it can learn TM-Dig, there's no any gen a Marowak-Alolan cannot learn the TM-DIg
3. I let it learn TM-False Swipe in game (not from move relearner) and success, so what makes the different? Why "it CAN learn TM-False Swipe on gen 6"
You've proved the Marowak-Alolan cannot learn TM on gen 6 by
https://bulbapedia.bulbagarden.net/wiki/Dig_(move)
so please check also the
https://bulbapedia.bulbagarden.net/wiki/False_Swipe_(move)
it does the same thing.
Just want to know the game mechanism in PRO, because I bought the poke, and found out it cannot use the move, which i think doesn't make any sense to me, thanks for your time.