Pokemon Diamond/Pearl Easter Egg - Reference to the Mineral Games: Crystal, Gold, Silver

Upon entering Sunnyshore, head to the Northern Exit. You will see Jasmine, Who was the leader of Olivine City in Pokemon Gold, Silver, and Crystal. She will tell you that she cannot allow you to pass without beating the gym, and refer to the lighthouse being just like the one in her hometown, (Where you originally find her and have to deliver the medicine SecretPotion to her for the Sparkling Lighthouse's sick pokemon Amphy, an Ampharos.)She then proceeds to give you HM Waterfall after you obtain the badge from Sunnyshore's gym leader Volkner. Also upon meeting her, she asks you if you know the Johto Region, then says she wishes you knew how nice it was. You can also see her in Super Contests, with her trusty Steelix from GSC, Which she decided to name Rusty.
She will also watch contests from time to time.