One way to get PP Ups in Pokemon Scarlet and Violet is to find a PP Up auction in Porto Marinada. These are rare, however you will be able to snag yourself a bunch of PP Ups at once if you are lucky enough. The auction I personally witnessed had 15 PP Ups for sale. The final bid was a whopping 122,000 Money...
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PP Up can be bought at the Chansey Supply shops around Paldea for ₽10,000. This item will be available post-credits, which is when you finish the entire game
PP Up can be obtained as a reward upon completing Tera Raid Battles. This item can drop from 6★ Tera Raid Battles.
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Hope this helps!
