How do you change Keldeo and Meloetta's form in Pokemon Omega Ruby and Alpha Sapphire?

Question

I am wondering because I have a Keldeo and a Meloetta that need form changing.

Answer 1

Another move tutor can be found in Crooner's Café, who will teach Keldeo and Meloetta their respective signature moves, Secret Sword and Relic Song.

If you bring Keldeo and/or Meloetta to a man in Crooner's Café, he will teach them Secret Sword (Keldeo) or Relic Song (Meloetta). Upon teaching Keldeo Secret Sword, it will change forms. To change Meloetta's form, you must use Relic Song in battle. However, Meloetta cannot be in Pirouette form out of battle.

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