Well, apparently there have been a few appearances. Look at the quote below:
This card was depicted in The Power of One as the object that started Lawrence III's collection. The card was the only object from his collection still in his possession at the end of the movie. This was the second appearance of a TCG card in the anime, after the depiction of Dark Primeape in the Japanese version of EP073. No more TCG cards would appear in the anime until Pearls are a Spoink's Best Friend.
Dark Primeape - EP073 Bad to the Bone
Notably, in AG079 Pearl's are a Spoink's Best Friend
As you can see, multiple TCG cards appear. I'm not gonna put up pictures since mods wouldn't approve. However, I don't think the cards shown exist since on the episode's page on Bulbapedia doesn't link to a specific TCG card page. But yet again, Bulbapedia is a contribution source so I may be wrong.
Whatever, hope I helped. :)