How to Unlock Tornadus
After defeating Giratina at the Temple of Sinnoh during the postgame, you can receive Request 94 “Incarnate Forces of Hisui” from Cogita upon entering Galaxy Hall. This will make Tornadus appear in Alabaster Icelands.
More precisely, Tornadus can be found roaming around Bonechill Wastes during snowstorms. It’s in the same area where the alpha Glalie is. You can quickly get there by gliding north from the starting point. Tornadus can be slightly hard to see because he’s covered by white-colored wind that camouflages with the snow.
How to Catch Tornadus
Tornadus, like the other Incarnates, is a very frustrating Pokémon to catch. When Tornadus notices you, the cheekly bugger will go flying backwards at high speed, while often creating multiple tornadoes to hinder you. Getting hit by a tornado will also cause frostbite. Chasing Tornadus head on is a recipe for disaster.
Before heading out, we recommend stocking up on Smoke Bombs and Stealth Spray. You can craft these yourself or buy them from the general stores. When you arrive at Bonechill Wastes, we suggest clearing out the trash, ahem, the Glalie wandering around. This includes the alpha. Otherwise they can be a nuisance later on.
Once you’ve removed all/most of the distractions, apply a Stealth Spray on yourself. Next sneak up behind Tornadus or intercept him from the sides. He will follow a pre-determined path, so you shouldn’t lose track of him. To prevent Tornadus from seeing you, throw Smoke Bombs to obscure yourself.
Once you’re near Tornadus, throw something at him to dispel his wind shield. You could throw a Pokémon, mud, more Smoke Bombs, Wing Balls etc. After dispelling the shield, Tornadus will roar and re-apply his shield. Don’t be disheartened; repeat this two more times.
On the third successful throw, Tornadus will be stunned after his shield disappears. Without delay, throw a Pokémon and trigger a battle. You could throw a Poké Ball and hope for a lucky catch, but if it fails, you’ll have to do everything again… While Tornadus is stunned, if you’re positioned behind him, you can catch him unawares during battle/catching.
During Pokémon battles, Tornadus can use his new signature move Bleakwind Storm, which deals Flying-type damage and may inflict frostbite. He can also use Extrasensory (Psychic), Crunch (Dark) and Hurricane (Flying). Pokémon that resist Flying moves, like Electric, Rock and Steel would be useful. However, it’s more important to have Pokémon with False Swipe to safely reduce his HP.
How to Change Tornadus into His Therian Form
When you’ve captured all four Incarnates and reached Research Level 10 for them, you can report back to Cogita at the Ancient Retreat. She’ll give you the Reveal Glass key item that will allow you to swap between their current Incarnate forms and their beast-like Therian forms.