Most Pokémon in this Egg Group are enigmatic in appearance, and the name reflects this. Its many members are based on a variety of things such as gases, blobs, inanimate objects and soft-bodied organisms. Most are capable of floating off the ground. Many of its members are Ghost-type Pokémon.
Ralts' evolutionary line is in this group despite having more Human-Like qualities.
The majority of members in this Egg Group are exclusive to it. Very few members are capable of breeding with Pokémon of other groups.