| 1 | Red, Blue | Almost invisible, this gaseous Pokémon cloaks the target and puts it to sleep without notice. |
| 1 | Yellow | Said to appear in decrepit, deserted buildings. It has no real shape as it appears to be made of a gas. |
| 1 | Stadium | Made of a thin, gas-like substance that induces fainting if you get enshrouded in it. Will not appear if it is very windy. |
| 2 | Gold | With its gas-like body, it can sneak into any place it desires. However, it can be blown away by wind. |
| 2 | Silver | Its thin body is made of gas. It can envelop an opponent of any size and cause suffocation. |
| 2 | Crystal | It wraps its opponent in its gas-like body, slowly weakening its prey by poisoning it through the skin. |
| 2 | Stadium 2 | With its gas-like body, it can sneak into any place it desires. However, it can be blown away by wind. |
| 3 | Ruby, Sapphire | Gastly is largely composed of gaseous matter. When exposed to a strong wind, the gaseous body quickly dwindles away. Groups of this Pokémon cluster under the eaves of houses to escape the ravages of wind. |
| 3 | Emerald | When exposed to a strong wind, a Gastly's gaseous body quickly dwindles away. They cluster under the eaves of houses to escape the ravages of wind. |
| 3 | FireRed | A being that exists as a thin gas. It can topple an Indian elephant by enveloping the prey in two seconds. |
| 3 | LeafGreen | Almost invisible, this gaseous Pokémon cloaks the target and puts it to sleep without notice. |
| 4 | Diamond | This Pokémon's body is 95% made up of gases, which are blown away by strong gusts of wind. |
| 4 | Pearl | A Pokémon born from poison gases. It defeats even the largest foes by enveloping them in gas. |
| 4 | Platinum | Born from gases, anyone would faint if engulfed by its gaseous body, which contains poison. |
| 4 | HeartGold | With its gas-like body, it can sneak into any place it desires. However, it can be blown away by wind. |
| 4 | SoulSilver | Its thin body is made of gas. Despite lacking substance, it can envelop an opponent of any size and cause suffocation. |
| 5 | Black, White, Black 2, White 2 | Born from gases, anyone would faint if engulfed by its gaseous body, which contains poison. |
| 6 | X | Its body is made of gas. Despite lacking substance, it can envelop an opponent of any size and cause suffocation. |
| 6 | Y | Born from gases, anyone would faint if engulfed by its gaseous body, which contains poison. |
| 6 | Omega Ruby, Alpha Sapphire | Gastly is largely composed of gaseous matter. When exposed to a strong wind, the gaseous body quickly dwindles away. Groups of this Pokémon cluster under the eaves of houses to escape the ravages of wind. |
| 7 | Sun | Should a strange light be seen flickering in an abandoned building, Gastly is lurking there. |
| 7 | Moon | Although Gastly is barely visible, when it's near, a faint sweet smell lingers. |
| 7 | Ultra Sun | It's said that gas emanating from a graveyard was possessed by the grievances of the deceased and thus became a Pokémon. |
| 7 | Ultra Moon | Poisonous gas comprises 95% of its body. It's said that the remaining 5% is made up of the souls of those who died from the gas. |
| 7 | Let's Go, Pikachu!, Let's Go, Eevee! | Said to appear in decrepit, deserted buildings. It has no real shape, as it appears to be made of a gas. |
| 8 | Sword | Born from gases, anyone would faint if engulfed by its gaseous body, which contains poison. |
| 8 | Shield | With its gas-like body, it can sneak into any place it desires. However, it can be blown away by wind. |
