Castform locations — where to catch

In Sinnoh (Diamond, Pearl & Platinum)

• Trophy Garden — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Pokéwalker — Walk

In Hoenn (Ruby, Sapphire & Emerald)

• Route 119 — Gift

Other games (5)

• Brilliant Diamond / Shining Pearl (Gen 8): Trophy Garden
• Ultra Sun / Ultra Moon (Gen 7): Alola Route 17, Exeggutor Island, Haina Desert, Lush Jungle, Malie Garden, Mount Lanakila, Tapu Village
• Sun / Moon (Gen 7): Alola Route 17, Exeggutor Island, Haina Desert, Lush Jungle, Malie Garden, Mount Lanakila, Tapu Village
• Omega Ruby / Alpha Sapphire (Gen 6): Hoenn Route 119
• Black 2 / White 2 (Gen 5): Unova Route 6

Castform — full Pokédex entry