The Pokémon Trading Card Game is still very much alive and continues to receive sets based on the new Pokémon games to this day. It isn't just characters from the Pokémon video games that appear on the cards, as people who attend showings of Pokémon: Detective Pikachu will receive two cards featuring characters from the film, one of which is Detective Pikachu.
The Pokémon Trading Card Game is receiving a mini-set that is based on Pokémon: Detective Pikachu and will contain eighteen cards that feature images of the Pokémon from the movie, rather than artwork created specifically for the game. There will also be special "Case File" sets that come with exclusive cards and merchandise from the film, including GX variants of the movie versions of Charizard, and Greninja.
According to Polygon, anyone who goes to see Pokémon: Detective Pikachu on its opening weekend will receive a free pack of two cards, one of which is randomly chosen from the Detective Pikachu set, while the other is guaranteed to be a card featuring Detective Pikachu. The promotion only goes for on as long as supplies last, so a busy opening weekend may ensure that not everyone receives a free pack of cards.
The release of exclusive Pokémon Trading Card Game cards during theatrical showings of Pokémon films has been going on since the beginning of the movie series. There is an entire set of promotional cards released by Wizards of the Coast that were given away during showings of Pokémon: The First Movie - Mewtwo Strikes Black, which are referred to as the Wizards Black Star Promos by the fans. Pokémon the Movie: I Choose You! also gave away exclusive Ash's Pikachu cards at certain showings back in 2017.
The Detective Pikachu card is similar to most of the promotional cards released for the Pokémon Trading Card Game, in that it doesn't have much use in terms of competitive play and is just a fun extra, as well as something to encourage collectors to see the film.
Pokémon: Detective Pikachu is due to be released in theaters on May 10, 2019.