KittyTikara says: "I created these eggs because I found that I was missing C1's gorgeous eggs while playing C1. So I added the eggs from C1 to DS and created some from the Creatures Village eggs. Hopefully they can brighten up your DS worlds as much as they have mine."
Make sure to back up your original eggs.c16 before installing. They might work in C3 standalone but I haven't tested it myself.