From Bulbapedia, the community-driven Pokémon encyclopedia.
The Undiscovered Egg Group (Japanese: タマゴみはっけん Eggs Never Discovered), known in Pokémon Stadium 2 as the No Eggs Egg Group, is one of the fifteen Egg Groups.
The Undiscovered Egg Group is characterized by its members' inability to breed. Except for Nidorina, Nidoqueen, and Unown, all of the Pokémon in the group are either baby Pokémon or legendary Pokémon.
Baby Pokémon are designated for this group due to them being too immature to breed, while legendary Pokémon are included to prevent players from breeding them (with the exception of Manaphy). The reason why Nidorina and Nidoqueen are in this group has been widely speculated since their inclusion in it in Generation II.
Only in this Egg Group
- This group is the only one besides the Ditto Group in which all members are in a single group, since being a member of any other Egg Group would defeat the purpose of being in the Undiscovered group.
- Nidorina and Nidoqueen are both in this group and therefore cannot breed; however, their respective male counterparts Nidorino and Nidoking, as well as their pre-evolution Nidoran♀ and its male couterpart Nidoran♂, are able to do so.
- The only legendary Pokémon not in this Egg Group is Manaphy, which is in the Water 1 and Fairy groups.
- As of Generation V, this is the only Egg Group where all types are represented by at least one Pokémon.