Collectors looking for cards with an edge within the Pokmon community should be sure to consider the deck list, and consider picking up some of the more expensive cards
Look closely at the shape, size, and alignment of these symbols
The new theory presented by @pokemonrevolution suggests sheets are stacked on top of each other before the 1st edition stamp ink was dry, causing both the imprints at the back of the cards, as well as the Grey stamps
However, there are some other places where you can make money: Here are a few options: Other Online Platforms
For example a creature might only have Hexproof while it's untapped
Given that Dragapult is such a relatively new Pokemon that hasn't featured in many generations, it's no surprise that some of the most expensive cards are from its debut sets