The egg groups are a classification used in the Pokémon games that defines which Pokémon are compatible with others when it comes to breeding. If two Pokémon are not in an identical egg group, they cannot breed at all. One Pokémon can be of one or two groups.
The fact that two Pokémon are part of the same egg group originates the egg moves, that are those moves a Pokémon can inherit from the father, even though the mother doesn't know them. In the sixth generation games, the moves can be inherited from either the father or the mother.
Here are some examples:
|Seed Bomb||Seed Bomb|
|Venusaur ♂||+||Breloom ♀||=||Shroomish|
|Iron Tail||Iron Tail|
|Aggron ♂||+||Haxorus ♀||=||Axew|
|Xatu ♂||+||Noivern ♀||=||Noibat|
|Scrafty ♂||+||Floatzel ♀||=||Buizel|
List of egg groups
The undiscovered (no eggs in Pokémon Stadium 2) egg group consists of 72 Pokémon.
The Pokémon in this egg group can't breed, that means they will never have an egg, not even with a Ditto. They are the Legendary Pokémon (except for Manaphy and Phione), the Baby Pokémon, Unown, and Nidorina and Nidoqueen (the reason Nidorina and Nidoqueen are not used is that they have correspondent males, so the males are used instead).
The Ditto egg group consists of only one Pokémon.
Egg group 2. The bug egg group consists of 68 Pokémon, most of them being Bug-type Pokémon, if not, at least that have physical bug appearance.
Egg group 3. The flying egg group consists of 50 Flying-type Pokémon.
Egg group 4. The human-like (humanshape in Pokémon Stadium 2) egg group consists of 52 Pokémon. Those Pokémon have certain resemblance to humans. Most of this group's Pokémon are Psychic or Fighting-type Pokémon.
Egg group 6. The amorphous (indeterminate in Pokémon Stadium 2) egg group consists of 49 Pokémon, which can't be compared to real life animals. Most of these Pokémon are Poison-, Psychic- and Ghost-type Pokémon.
Egg group 7. The field (ground in Pokémon Stadium 2) egg group consists of exactly 200 Pokémon. Most of those Pokémon are terrestrial, but some of them can also live in water. This egg group contains a wide variety of Pokémon.
Egg group 8. The water 1 egg group consists of 87 Pokémon. It is formed by Water-type Pokémon, which most of them have extremities that allow them to sustain their lives in the water as well as on land.
Egg group 9. The water 2 egg group consists of 23 Pokémon. It is formed mostly by Water-type Pokémon, which lack of limbs and only have fins to live in the water.
Egg group 10. The water 2 egg group consists of 29 Pokémon. It is formed partly by Water-type Pokémon. In this egg group also includes fossils and arthropods. The arthropods are a group of invertebrates where we can find crustaceans and arachnids.
Egg group 11. The monster egg group consists of 75 Pokémon. The Pokémon in this egg group have the appearance of either a beast, a dinosaur or a reptile.
Egg group 12. The fairy egg group consists of 47 Pokémon. The Pokémon in this group are considered "fairies" thanks to their lovely and very cute appearance. After Generation VI onwards, many of these Pokémon are precisely Fairy-type Pokémon.
Egg group 13. The dragon egg group consists of 45 Pokémon. They are mainly Dragon-type Pokémon. Most Pokémon in this egg group have appearance of dragons, serpents, lizards or similar reptiles.