Nincada locations — where to catch

In Sinnoh (Diamond, Pearl & Platinum)

• Eterna Forest — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• National Park — Walk

In Hoenn (Ruby, Sapphire & Emerald)

• Route 116 — Walk

Other games (4)

• Brilliant Diamond / Shining Pearl (Gen 8): Eterna Forest
• Sword / Shield (Gen 8): Bridge Field, Dappled Grove, Route 5, Galar Route 5, Rolling Fields, South Lake Miloch, West Lake Axewell
• Omega Ruby / Alpha Sapphire (Gen 6): Hoenn Route 116
• X / Y (Gen 6): Friend Safari, Kalos Route 6

Nincada — full Pokédex entry