Princess Salvia lives in a palace in Katakuri Town (カタクリタウン) . She switched places with Dawn since they look almost the same and then participated in the Katakuri Town Pokémon Contest with her Togekiss.
In the final round, she faced Jessie and was able to defeat her after Dawn was able to encourage her enough to battle back. Realizing that Jessie needed the ribbon from the contest to enter the Grand Festival, she gave her the ribbon.
Princess Salvia gave her Togekiss to Dawn to help her in the Grand Festival as thanks for trading places with her.