Voltorb locations — where to catch

In Paldea (Scarlet & Violet)

• East Province (Area Three) — Walk
• East Province (Area Two) — Walk
• Tagtree Thicket — Walk
• West Province (Area Three) — Walk

In Hisui (Legends: Arceus)

• Celestica Ruins — Walk
• Sacred Plaza — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Route 218 — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Johto Safari Zone — Walk
• Olivine City — Trade
• Route 10 — Walk
• Team Rocket HQ — Static Encounter, Walk

In Hoenn (Ruby, Sapphire & Emerald)

• New Mauville — Static Encounter, Walk

In Kanto (FireRed & LeafGreen)

• Kanto Power Plant — Walk
• Route 10 — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 10 — Walk
• Team Rocket Base — Static Encounter

In Kanto (Red, Blue & Yellow)

• Kanto Power Plant — Static Encounter, Walk
• Route 10 — Walk

Other games (4)

• Brilliant Diamond / Shining Pearl (Gen 8): Route 218
• Let's Go, Pikachu! / Let's Go, Eevee! (Gen 7): Kanto Power Plant
• Omega Ruby / Alpha Sapphire (Gen 6): Route 110, New Mauville
• XD (Gen 3): Pokespot

Voltorb — full Pokédex entry