During the story you will be tasked with obtaining the Phoenix Mirror, and this will lead to you visiting Bunkado Antiques in Dobutia.
Whilst there, combat move scrolls are on the shelf on the left, and I believe there are 6 total.
For me, I made a save, then purchased the cheapest scrolls. 4 of them for roughly 6,000 as I believe the get one move automatically at the start of the game.
Once purchased you need to access your menu and view them for them to unlock. Once this is done 5 times and the cheevo pops feel free to reload your save and carry on.