players have already discovered a set of cards that show several species of Pokémon living together in relative harmony. One of the joys of the Pokemon TCG is that sets will occasionally feature linked cards, with multiple Pokémon in a single scene split up over several cards.
To get the whole picture, you need to collect all of the cards. has also adopted this tradition. With the recent release of Space-Time Smackdown, players have already discovered a new set of connected Pokémon cards.
As pointed out by NoobJaeger on Reddit, the new Skarmory, Magcargo, and Rhydon cards all feature new art with the respective Pokémon underground inside of Stark Mountain.
The cave walls and ceiling all have a distinctive pattern to them, although their cause isn't immediately obvious when looking at just one piece of art. Heatran's card shows the source of these strange patterns — they are Heatran's footprints, caused by the Pokémon traversing through the cave.
Heatran's Illustration Rare card brings all four cards together, with each Pokémon existing on different lairs in the cave, with Heatran in the middle.