From Bulbapedia, the community-driven Pokémon encyclopedia.
The Water 3 Egg Group (Japanese: 水中③グループ Underwater 3 Group) is one of the fifteen Egg Groups. Like its counterparts Water 1 and Water 2, it is mostly made up of Water-type Pokémon. As of Generation VII, 33 Pokémon belong to this group.
Characteristics
The Water 3 Egg Group is mostly characterized by its members' resemblance to aquatic invertebrates; most are Water types. This group also includes a number of Fossil Pokémon, totaling a little more than half of them.
It is a relatively small Egg Group. Most Pokémon that are capable of breeding into other Egg Groups breed into the Water 1 Group.
Pokémon
Only in this Egg Group
In this and another Egg Group
In other languages
