Certain Mewtwo cards in the are worth by far the most money. With roughly 9,000 English cards and 7,000 Japanese cards, just 44 of these feature Mewtwo. However, the Legendary Psychic-type Pokémon is frequently included in new sets to attract collectors and diehard fans. Mewtwo’s popularity is likely due to featuring in the first ever movie and lending a darker edge to the otherwise wholesome universe.
For these reasons, rare Mewtwo cards regularly command hundreds of dollars on online markets, with some one-off sales reaching into the thousands. Typically, the price of a card is based on its rarity, artwork, utility, and popularity. One-off sales can be caused by flukes of circumstance or particularly urgent buyers, so valuing a Mewtwo card is more appropriately done by looking at their average resale value on sites like TCGplayer and PriceCharting (all listed prices are from the time of writing).
Related: Pokémon TCG: 10 Most Expensive Collection Boxes
This is the first Mewtwo card ever produced, which means it would be easy to assume it's a shoo-in for the most popular base set card. But when the card was first released, it was initially only mildly popular. The first movie hadn’t been released yet, so Mewtwo was simply's endgame Pokémon. While the average price for a base set Mewtwo isn’t so high, according to TCGplayer's market price, PriceCharting shows that the coveted Base Set 1st Edition Shadowless Holo Mewtwo card can sell for prices approaching $20,000.
A couple of Rocket’s Mewtwo cards have been released, but this card comes from the original set. The set prominently featured Pokémon associated with key trainers from the games, such as Blaine’s Arcanine. Rocket’s Mewtwo demands a high price (via TCGplayer)
Read more on screenrant.com