The game features both a single-player mode in which you play against a computer as well as an online version that allows you to challenge other players as well as a full deck management system.
You can grab Pokemon TCG for free on any iPad that has a Retina display (non-Retina models aren’t supported). The App Store description is below:
PLAY, TRADE, AND CHALLENGE OTHER PLAYERS AROUND THE WORLD Have fun learning and mastering the Pokémon Trading Card Game Online! Practice against the computer or go head to head with your friends or other players from around the world. Unlock cards and decks as you play to build up your collection and make truly unique decks. Your decks and card collection are stored as a part of your Pokémon Trainer Club account, allowing you to switch between iPad and desktop with ease.
EASY TO START: Choose from Grass, Fire, or Water decks, step right into a game, and learn as you go in an easy play experience.
EXPAND YOUR COLLECTION: Earn cards, open booster packs, trade with other players, and build the perfect deck around your favorite cards. Your collection grows with you!
CUSTOMIZE YOUR EXPERIENCE: Build your own decks, customize the look of your cards, deck boxes, and avatar, and join your friends online.
HONE YOUR SKILLS: Play against the computer until you are ready to challenge other players.
CHALLENGE THE WORLD: When you feel your deck design is ready, challenge other players or join a tournament to show your skill and knowledge.