* "Hollow" is not a recognized term in Pokemon card collecting. There are no "hollow" Pokemon cards in the traditional sense.
* Cards are made of cardboard. This means they are inherently solid.
* Some cards might *feel* hollow if they're damaged. This could be from a bend or crease making the card feel uneven.
However, there are some things to look for when determining if a Pokemon card is authentic and valuable:
* Cardback: The back of the card should have a consistent design and color. If it's faded or uneven, it could be a fake.
* Foil: If the card has a foil stamp, make sure it's smooth and doesn't have any wrinkles or air bubbles.
* Printing: The text and images should be crisp and clear.
* Holofoil: Holofoil cards should have a distinct holographic effect that doesn't smear or fade.
* Edges: The edges of the card should be straight and smooth, not jagged or uneven.
If you're concerned about the authenticity of a card, it's best to consult with a reputable Pokemon card dealer or collector.