Pokemon Legends Arceus Incarnate Forces of Hisui Request

Where To Find Request
After beating the game, go to Galaxy HQ and speak to Cogita.

How To Complete
Landorus is found on Ramanas Island in the Obsidian Fieldlands. Thundurus is found in the Cobalt Coastlands, during Heavy Rain Fall weather. Tornadus is found in the Bonechill Wastes area of the Alabaster Icelands, during the Blizzard weather. After capturing all 3 of them, return to Cogita.

You can find and catch Tornadus, Thundurus, Landorus at the locations listed below in PLA.

In Bonechill Wastes of Alabaster Islands during Blizzard, via Quest from Cogita

In the water of Cobalt Coastlands by Pillars of Coastland Campsite, During Heavy Rain Fall via Quest from Cogita

Ramnas Park in Obsidian Fieldlands After Receiving Quest from Cogita