Every first-edition Pokémon card has a stamp, so if your card doesn’t have one, it may be from a different base set.
Shadowless cards are still considered valuable since they were part of a smaller print run.
Another subtle change between editions is the font thickness for a Pokémon’s HP in the top right corner. Unlimited cards have a bolder font than their shadowless or first-edition counterparts. Trainer and Energy cards don’t have drop shadows on the art, so the only ways to tell the difference between editions are the copyright dates. Unlimited cards are the least valuable of the base sets since they’re the most common.
Blastoise (holographic): $4,150–31,334 USD Venusaur (holographic): $2,595–12,299 USD Chansey (holographic): $1,905–27,412 USD Mewtwo (holographic): $1,841–13,100 USD Even the original starting Pokémon, like Squirtle, Bulbasaur, and Charmander are worth around $200–1,000 USD.
Charizard (holographic): $5,449–31,402 USD Blastoise (holographic): $968–4,765 USD Alakazam (holographic): $627–2,310 USD Gyarados (holographic): $289–2,300 USD Mewtwo (holographic): $425–3,725 USD
Pokémon cards that you’ve played with are usually worth less as well since they may have slight nicks or bends in the material.