There is an option to manually add the card, but they default to Pokmon as the set, so if I manually enter my card its a Cooper Flagg Pokmon card
Once the maximum number of copies has been reached for a card type, duplicates will get converted into Credits that can be exchanged for any card that a player does not already have in their collection (up to the maximum number of copies allowed)
As such, finding cheap yet powerful cards to upgrade your deck isnt hard at all
Competitive Brawl Ajani, Nacatl Pariah // Ajani, Nacatl Avenger Lutri, the Spellchaser Nadu, Winged Wisdom Oko, Thief of Crowns Old Stickfingers Ragavan, Nimble Pilferer Rusko, Clockmaker Tajic, Legion's Valor Tamiyo, Inquisitive Student // Tamiyo, Seasoned Scholar Wrenn and Six Though Competitive Brawl shares many features with its Historic counterpart, like 25 starting life, a commander, and a 99 card deck constrained by the commander's color identity, it has a unique ban list of ten extremely powerful, oppressive commanders