The official Pokémon website has announced that on May 18th, 2019 from 11am to 4pm, participating Walmart locations in the United States will be distribution a Bulbasaur Promo card and a Detective Pikachu movie poster.

Get a Pokémon TCG: Detective Pikachu Promo Card at Walmart

Visit participating Walmart stores on May 18 to get a card featuring Bulbasaur and a POKÉMON Detective Pikachu movie poster.

Celebrate the release of the POKÉMON Detective Pikachu movie during a special event at Walmart! Stop into a participating Walmart on May 18, 2019, from 11 A.M. to 4 P.M. in your local time zone to receive a pair of special giveaways—a Pokémon TCG promo card featuring the big-screen version of Bulbasaur, plus a POKÉMON Detective Pikachu movie poster. These great giveaways are only available while supplies last, so don't miss out!

See the rest of the cards based on the POKÉMON Detective Pikachu movie and get more details on the Pokémon TCG: Detective Pikachu expansion at the official site.

Sources: https://www.pokemon.com/us/pokemon-news/get-a-pokemon-tcg-detective-pikachu-promo-card-at-walmart/ and https://www.pokemontcg.com/en-us/detective-pikachu/