Those cards became highly sought after for their rarity after thousands were dumped into the Hudson River in 1960 after overproduction
The alternate colorway gives Mewtwo an ethereal, otherworldly appearance that fits perfectly with the character's lore as a genetically engineered psychic powerhouse
Like most Starter Decks, it is simplistic and easy to understand but at the cost of power
This outrage sparked some distasteful reaction from the community, resulting in threats towards the members of the Rules Committee, which in turn prompted them to hand over their involvement in the format to WotC, a corporation that could take the brunt of backlash like this without its members being in any discernible danger
However, if instead the creature's power is increased to 3 or greater after the ability resolves, it still can't be blocked that turn
There is a way around this though and that's by spending Pack Points