In Pokémon Scarlet and Violet, you can catch a future version of Donphan called Iron Treads. However, the new Paradox Pokémon can only be found in a specific location on the map after its spawn is unlocked through a story campaign.
Where to catch Iron Treads (Paradox Donphan) in Pokémon Scarlet & Violet?
Iron Treads is only available in Pokémon Violet after you have completed the campaigns Victory Road, Starfall Street, and Path of Legends. Once you have finished the three storylines, a hidden fourth campaign will open up that takes you to the Great Crater of Paldea. The Paradox Pokémon will not spawn until you have turned on the three research stations in the story and descended into the deep caverns of Area Zero. You will know you have traveled far enough, as a special cutscene that introduces the Paradox variant will automatically be triggered. After the story segment is over, you will now be able to catch Iron Treads in the Crater of Paldea.
Where is Iron Treads spawn location in Pokémon Scarlet & Violet?
Iron Treads spawns in Area Zero of the Great Crater of Paldea. The new Paradox Pokémon is impossible to miss if you are completing the final story quest in the game, as it will appear everywhere as a wild spawn in the crater caverns. You will also be able to fast travel back to the Zero Gate once you have beaten the game to pick up Iron Treads anytime you want. The quickest way to find Paradox Donphan is to fast travel to Research Station No. 4 and then look around the caverns. If you just ride back and forth in the area you will see a wave of Iron Tread's popping into the overworld.
How to get Great Tusk (Paradox Donphan) in Pokémon Scarlet & Violet?
In Pokémon Scarlet, players get an ancient version of Paradox Donphan called Great Tusk instead. Just like Iron Treads, though, the new Pokémon is located in the exact same spot in Area Zero. Great Tusk spawns in the Great Crater of Paldea once you have completed all three story campaigns. The best way to get both Paradox versions of Donphan is to trade with another player with the opposite version of your game. Because both Iron Treads and Great Tusk spawn in large quantities once they are unlocked, it's easy enough to catch extras so that you can swap with another trainer.
For more information on Pokémon Scarlet and Violet, check out Where to find Leader's Crest to evolve Kingambit here on Pro Game Guides.