Pauper is an Unlimited format where you can only use cards with a Common or Uncommon rarity.
When I first learned about Pauper, I thought about my favorite type of Unlimited deck, Lost World, which is based off of an uncommon card. This is my take on a Pauper Lost World deck.
Use Mime Jr. to remove cards from your opponent's deck and use Chatot G, Hiker, Trick Shovel, and Chip-Chip Ice Axe to control those cards. Scoop Up Net works as both a switch card (Recycle Energy goes to your hand) and a way to reuse Chatot without attacking with it. Attacking with Chatot can also be good to guarantee a certain trainer that you need, as it's hard to get Professor Oak without access to Computer Search. Girafarig can also be a good to get your opponent's Pokémon in the lost zone with Get Lost, especially in combination with Trick Shovel or Avery. Jirachi is key to not getting demolished by decks that put damage counters. If there is a common or uncommon card that prevents damage to the bench, please leave a comment because I would include it. If you have any questions or suggestions, please leave a comment.
Happy trolling!