Recommended Level: 28+
The potential third Titan hunt you'll undergo in Pokémon Scarlet and Violet, The Search for the Lurking Steel Titan will take you along the eastern coast of Paldea to the rocky land of East Province (Area Three). A mass of mined dirt stretching from the sea to the core of Paldea, it's a tough land for tracking down a Titan... or at least it would be, if the thing didn't stick out like a sore thumb.
To reach and battle the Lurking Steel Titan you'll need to leave Mesogoza and head east. Swing north once you leave Artazon and travel along the coast to Levincia. Beyond Levincia you'll find East Province (Area Three), and you'll get a call from Arven, your ever-vigilant partner in the Titan hunt, as you head into the western section of the area. Once Arven calls you won't be too far from the Titan.
Follow the main road through East Province (Area Three) until you see a massive pit with a few caves on your right. Beside it is a hill. Keep walking past the hole and the hill and take a right once you're beyond the rocks blocking your view. There's another, smaller hole to the north, and once you peek inside you'll see the Titan's head poking out of the dirt. It will flee when you get close, so you'll need to hurl a Poké Ball at it to engage the Titan in combat.
Orthworm, the Lurking Steel Pokémon
Well, that's... something. Orthoworm is a massive Steel-type Pokémon that is tougher than it looks, though still not that bad. It favors attacking you with Iron Tail, a strong - but inaccurate - Steel-type move, as well as the Normal-type Headbutt. Both hit fairly hard, though if you bring out something with a high defence you shouldn't have that much trouble weathering its attacks. Orthworm will restore its health if you use Ground-type moves on it, thanks to its ability, so Fire- and Fighting-type moves are your best bet.
Do enough damage and Orthworm will smash open a tunnel and escape. This time it will appear in the huge pit from earlier, and it will keep moving between a preset number of spaces. Get on your mount, goad Orthworm into moving to another location, and dash over to it. Get there more or less as Orthworm is appearing and it will smash open yet another hole, this one to the Herba Mystica it is hoarding.
The second battle is, per usual, alongside Arven, and he's brought a Toedscool along to play. Its Ground- and Grass-type will keep Toedscool largely safe, and the two of you can bring the Titan down for good. Use the same moves you did previously, and be prepared to do the lion's share of the damage. Toedscool is handy, but it won't dish out a ton of pain.
Once the battle is over Arven will retrieve the Salty Herba Mystica and create some tasty sandwiches. You'll earn another Titan's Badge, and your mount will hereafter be able to jump higher. This will allow you to reach higher ledges than before, making exploration and item retrieval much easier. Once you've beaten the Orthworm Titan you'll also start running into much smaller Orthworms in the pit where you fought the beast, and can catch them for your team. (Though be prepared for a long fight. They're hard to catch.)