NationalDex
Go
Red / Blue
Yellow
Red Green Japan
Blue Japan
Gold / Silver
Crystal
Ruby / Sapphire
Emerald
FireRed / LeafGreen
Colosseum
Xd
Diamond / Pearl
Platinum
HeartGold / SoulSilver
Black / White
Black 2 / White 2
X / Y
Omega Ruby Alpha Sapphire
Sun / Moon
Ultra Sun / Ultra Moon
Let's Go Pikachu / Eevee
Sword / Shield
The Isle of Armor
The Crown Tundra
Brilliant Diamond Shining Pearl
Legends: Arceus
Scarlet / Violet
The Teal Mask
The Indigo Disk
Legends Za
Mega Dimension
Gengar Gmax was introduced in Generation 1
This Pokémon isn't available in Generation VIII.