Johto hint. DP also opened up with a reference to the red Gyarados, Park Balls were gold and silver and their names were a reference to Park Balls in Gen II. Not only that, but DP reintroduced
>Day and night cycle, complete with visuals, alternate encounters, and specific Trainer battles
>The day of the week having an effect on certain NPCs
>Online multiplayer from Japanese Crystal
>The PokéCom Center essentially being remade as the GTS
Also, the names Diamond and Pearl connect to Gold and Silver in Japanese through the Japanese word for Platinum.
