The ancient cave paintings in Celestic Town depict a different set of mythical Pokémon:
* Dialga: This painting depicts the legendary Pokémon Dialga, representing Time.
* Palkia: This painting depicts the legendary Pokémon Palkia, representing Space.
* Giratina: This painting depicts the legendary Pokémon Giratina, representing Anti-matter or the Distortion World.
These three Pokémon, along with their respective lakes, are essential to the plot of Pokémon Pearl and Diamond. They represent the forces that shaped the world and the balance that must be maintained.
The cave paintings are a clue that leads players to understand the connection between the three legendary Pokémon and the origins of the world.
Perhaps you are thinking of a different Pokémon game or a fan-made creation? If you can provide more details about what you saw, I may be able to help you further.