The Move Reminder is a special type of Move Tutor found in the Pokemon Series that has the power to to teach your Pokemon moves that is has previously learned by leveling up that it no longer knows (as well as moves that it wouldn't learn until a much later level). In this game, the Move Reminder can be found in Indigo Plateau. However, in exchange for this service, the Move Reminder will require you to provide them with a Heart Scale (which can only be obtained randomly by playing with your Starter Pokemon).