In Pokemon Go, a Fast TM is a Technical Machine (TM) that allows players to change the Fast Attack of a selected Pokemon. By default, all Pokemon have two attacking moves: a Fast Attack and a Charged Attack. Fast Attacks deal a small amount of damage, while also powering up a Charged Attack. Charged Attacks can be used in Trainer Battles or Battle Training, and some Charged Attacks have extra boosts or drops. Fast TMs can teach a Pokemon a new Fast Attack, while Charged TMs can teach a Pokemon a new Charged Attack. Elite Fast TMs allow players to choose a Fast Attack to teach to a Pokemon, including Fast Attacks that were previously only available during events like Community Days or Raid Days. Elite Charged TMs allow players to choose a Charged Attack to teach to a Pokemon, including Charged Attacks that were previously only available during events like Community Days or Raid Days.

To use a TM, players need to go to their Bag, scroll down and select the item. The Pokemon overview screen will open, and players will be able to select a Pokemon for which they want the TM to be used. Players can use unlimited numbers of TMs on the same Pokemon. The chances of getting a specific move are different for Fast TMs and Charged TMs, and players can consult the GO Hub DB to see which moves are TM-eligible at the moment.

In summary, a Fast TM is a Technical Machine in Pokemon Go that allows players to change the Fast Attack of a selected Pokemon.