How to Catch Terrakion in Pokémon Black and White

Catch Cobalion. Terrakion will not appear until Cobalion is caught. Cobalion can be found on the third level of Mistralton Cave, where he will be waiting for you in the northwest corner. To find Mistralton Cave, Surf north on the river to the left of the Scientist's house on Route 6, bypass the rocks in the way, and Surf east on the river where you will see a cave entrance.

Prepare well. Terrakion is as difficult to catch as any other Legendary, with the lowest capture rate possible. If you have all you need, catching him will be easier. Bring strong Pokémon and plenty of healing items for your Pokémon.

• Have a Pokémon with False Swipe of at least Level 30. Axews can be found in Mistralton Cave knowing this move at Level 24 or higher. Professor Juniper will give you the TM once you have seen at least 30 Pokémon.
• Have a Pokémon who knows Strength.
• Own a Pokémon who can inflict paralysis, sleep, or freeze. Yawn, though it takes longer, is a more accurate way to make a Pokémon fall asleep than Hypnosis, so keep this in mind.
• Get, at a minimum, one Quick Ball, a few Timer Balls, 25 Dusk Balls, and 20 Ultra Balls. The more Poke Balls, the better.

Go through Victory Road and reach the Pokémon League. From the Pokémon League, backtrack to the gate where there is a cave entrance to the east. Go through here, go west down the stairs, south, and then west again along the narrow passage. You will see a different sort of cave entrance on the northern wall. Go through it and you will see Terrakion sitting in a small room, waiting for you. Save the game and then talk to him.

Attempt to catch him. Throw a Quick Ball at him on the first turn. It might catch him, it might not, but it's always worth a try, though only on the first turn.

• Avoid super-effective moves. Be careful - you don't want him to faint. If he does, you can always turn off the device and retry again, but be on the safer side!
• When you use False Swipe depends on how powerful your Pokémon who learned it is, but don't loose your chance - try in the yellow, and then red. When you see a tiny little sliver of HP, this is probably the lowest you can go.
• Putting him to sleep or freezing him will give you a higher rate of capture than paralysis, remember. Do one of those.