Generation 1 · Pokédex profile
Poison Gas Pokémon
Pokédex entry
Getting up close to a Koffing will give you a chance to observe, through its thin skin, the toxic gases swirling inside. It blows up at the slightest stimulation.
Battle data
Conditional evolutions can require additional game-specific prerequisites beyond the displayed method.
| Method | Location | Level | Evidence |
|---|---|---|---|
| Grass / ground | Burned Tower 1f | Lv. 14 | Source-indexed, not individually verified |
| Grass / ground | Burned Tower B1f | Lv. 16–17 | Source-indexed, not individually verified |
| Grass / ground | Fiery Path | Lv. 15–16 | Source-indexed, not individually verified |
| Grass / ground | Pokemon Mansion 1f | Lv. 28–30 | Source-indexed, not individually verified |
| Grass / ground | Pokemon Mansion 2f | Lv. 28–30 | Source-indexed, not individually verified |
| Grass / ground | Pokemon Mansion 3f | Lv. 28–30 | Source-indexed, not individually verified |
| Grass / ground | Pokemon Mansion B1f | Lv. 28–30 | Source-indexed, not individually verified |
| Surfing | Celadon City | Lv. 30–40 | Source-indexed, not individually verified |
Rare grass and Surfing encounters inherit the first native slot's level range. Supplemental fishing follows each rod's native slots. These ranges exclude Lure effects and randomizer replacements; eligibility restrictions still apply.
Data source: configured Grand Anthology Gen 1–9 species, forms and abilities. The website uses frame-cropped copies of the game's existing Pokémon sprites, which remain franchise/artist-owned assets. Some alternate forms use labeled default-form artwork when their individual sprite is unavailable. See acknowledgments for credits.