There are two types of Technical Machines corresponding two types of attacks in the game:
Fast TMs for Fast Attacks
and Charged TMs for Charged Attacks.
Details TM that can be used to teach a Pokémon a new, random Fast Attack.
In-game description This Technical Machine item is used to teach your Pokémon a new Fast Attack. Your Pokémon will acquire a new Fast Attack and forget their old Fast Attack.
Details TM that can be used to teach a Pokémon a new, random Charged Attack.
In-game description This item works like the Fast TM but it teaches the Charged Attack instead of a Fast Attack. Remember, to use a charged attack you need to select the element button underneath the bar.
Legacy moves are not able to be re-rolled. (as in you can change a legacy move for another move but you cannot get that legacy move ever again).