Where to catch Gastly

In Paldea (Scarlet & Violet)

• East Province (Area One) — Walk
• East Province (Area Three) — Walk
• East Province (Area Two) — Walk
• South Province (Area Four) — Walk
• South Province (Area One) — Walk
• South Province (Area Three) — Walk
• West Province (Area One) — Walk
• West Province (Area Three) — Walk
• West Province (Area Two) — Walk

In Kitakami (Scarlet & Violet – The Teal Mask)

• Apple Hills — Walk
• Mossfell Confluence — Walk
• Oni Mountain — Walk
• Paradise Barrens — Walk
• Wistful Fields — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 31 — Walk
• Route 32 — Walk
• Route 36 — Walk
• Sprout Tower — Walk
• Tin Tower — Walk

In Kanto (Red, Blue & Yellow)

• Pokémon Tower — Walk

Gastly — full Pokédex entry