From Bulbapedia, the community-driven Pokémon encyclopedia.
The Ditto Egg Group (Japanese: メタモン Metamon) is one of the fifteen Egg Groups. It is the only group which has only one member.
Ditto is the only Pokémon in the Ditto Egg Group, so all characteristics of this group are Ditto's. Ditto, which just belongs to this Egg Group, has the ability to breed with every member of every other Egg Group but the Undiscovered and Ditto Egg Groups.
Only in this Egg Group
- Pokémon in the Ditto group can breed with any Pokémon from any Egg Group, excluding the Undiscovered Egg Group. However, Ditto cannot breed with members of its own group, meaning that Ditto cannot be hatched from an Egg. The only exception is in Generation II.
- Since this group consists of a single Pokémon, it is naturally the Egg Group with the lowest number of types represented, with just one.