"Transform is the only way to see the battle animation of Cherrim’s Sunshine Form prior to Generation V, as Cherrim sent from a Poké Ball will always be sent out in Overcast Form, and Cherrim is not available in the wild in Generation IV. A Ditto that transforms into Cherrim, however, will play the animation of the alternate form if it escapes from a thrown Poké Ball."

— Transform (move)