The Phantom Cards seem to be based on the Mythical Pokémon (for comparison, the Legendary Cards seem to be based on the Legendary Pokémon). The Phantom Cards and Mythical Pokémon are named with the same Japanese word: "幻" (Illusory).
List of cards
Pokémon Trading Card Game
In Pokémon Trading Card Game, there are two Phantom Cards: Venusaur and Mew. They can only be obtained through Card Pop!. Due to an oversight in the way the Card Pop! mechanic determines which card you will get, the Phantom Venusaur card is left unobtainable. Because a player cannot Card Pop! with same partner save file again until both players have used the feature with fifteen others; causing their partner's ID to be overwritten in both save files, the Phantom Mew card is potentially the hardest card to acquire in the game. The Venusaur card was also distributed in real life with the purchase of the game's Japanese Guidebook or English Player's Guide. Both of these cards are needed for the Mysterious Pokémon Deck, making it unused due to the oversight.
The current and maximum number of cards is displayed in the Diary and the main menu screen, but each Phantom Card only counts if the player has it. For instance, if the player has all cards except the Phantom Cards in the first game, the number is shown as "226/226". If the player has 99 regular cards and 1 Phantom Mew, the number is shown as "100/227".
