Things You'll Need
Instructions
FireRed and LeafGreen
Speak with Bill on Cinnebar Island. He is found in the Pokemon Center.
Accept when Bill offers to take you to the Sevii Islands. The Tangela is found on Sevii Island One.
Walk to the Island One boathouse, and surf south until you reach Treasure Beach.
Walk around until you encounter a Tangela. They're common on Treasure Beach.
Weaken the Tangela until its health is red, and toss a Pokeball to capture it.
Save your game and quit.
Diamond and Pearl
Place "Pokemon: FireRed" or "Pokemon: LeafGreen" in the DS's Gameboy Advance slot, and insert "Pokemon: Diamond" or "Pokemon: Pearl" in the main slot. Turn your DS on.
Select "Migrate Pokemon," and choose the Tangela. You can transfer five other Pokemon, too. After, you must wait at least 24 hours before you can transfer more.
Play through the game until you complete the main quest, earning the National Dex. With the National Dex, you unlock Pal Park, where your Tangela awaits.
Travel south of Sandgem to Route 211. There, you'll find Pal Park.
Present your National Dex, and go inside. Pal Park is divided into five region-types. Enter a forest region.
Walk around the forest until you encounter the Tangela. Throw a Pokeball at it to catch it.