Relic Song (Japanese: いにしえのうた - Ancient Song) is a Normal-Type attack introduced in Generation V. In addition to damage, this move also has a secondary effect of putting the targeted Pokémon to Sleep at a rate of 10%.
Additionally, Relic Song will change the form of Meloetta from its Aria Forme to its Pirouette Forme when this move is used in battle. This changes the typing of Meloetta from a Normal/Psychic Type to a Normal/Fighting Type.
Meloetta's Base Stats also change as well: when changing to Pirouette Forme, Meloetta's Base Attack, Defense and Speed Stats increase, but its Special Attack and Special Defense Base Stats decrease. Meloetta's Hit Points remain the same, however.
This extra effect only lasts until Meloetta is switched out.