* "Best" is subjective: What makes a card "best" depends on the context:
* Format: Is it Standard, Expanded, or a different format? Different formats have different card pools and power levels.
* Deck: What kind of deck is it being used in? A card that's amazing in one deck might be mediocre in another.
* Player skill: A skilled player can make even a "lesser" card powerful.
* Power shifts constantly: The Pokemon Trading Card Game is constantly evolving. New sets are released, new strategies emerge, and the "best" cards change over time.
* Multiple Mewtwo cards: There are multiple Mewtwo cards with different effects and abilities. Some are stronger than others.
Therefore, there's no single "best" card. It depends on the situation!
Instead of asking which card is "best," it's more productive to ask:
* What are the strongest cards in the current format?
* What are some of the most popular and effective decks right now?
* What are the key cards that make those decks work?
By looking at the game's current state and the cards used in strong decks, you can gain a better understanding of what makes cards effective and how they fit into the meta.