Metapod locations — where to catch

In Sinnoh (Diamond, Pearl & Platinum)

• Eterna Forest — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Ilex Forest — Headbutt, Walk
• National Park — Walk
• Route 2 — Walk
• Route 30 — Walk
• Route 31 — Walk
• Route 47 — Headbutt
• Viridian Forest — Walk

In Kanto (FireRed & LeafGreen)

• Route 24 — Walk
• Route 25 — Walk
• Viridian Forest — Walk

In Sevii Islands (FireRed & LeafGreen)

• Pattern Bush — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Azalea Town — Headbutt
• Ilex Forest — Headbutt, Walk
• Lake of Rage — Headbutt
• National Park — Bug-Catching Contest, Walk
• Route 2 — Walk
• Route 24 — Walk
• Route 25 — Walk
• Route 26 — Headbutt
• Route 27 — Headbutt
• Route 30 — Walk
• Route 31 — Walk
• Route 34 — Headbutt
• Route 35 — Headbutt
• Route 36 — Headbutt
• Route 37 — Headbutt
• Route 38 — Headbutt
• Route 39 — Headbutt

In Kanto (Red, Blue & Yellow)

• Route 24 — Walk
• Route 25 — Walk
• Viridian Forest — Walk

Other games (6)

• Sword / Shield (Gen 8): Bridge Field, Dappled Grove, Rolling Fields, South Lake Miloch
• Let's Go, Pikachu! / Let's Go, Eevee! (Gen 7): Viridian Forest
• Ultra Sun / Ultra Moon (Gen 7): Alola Route 5, Lush Jungle, Melemele Meadow
• Sun / Moon (Gen 7): Alola Route 1, Alola Route 5, Lush Jungle, Melemele Meadow
• X / Y (Gen 6): Santalune Forest
• Black / White (Gen 5): Unova Route 12

Metapod — full Pokédex entry