Cyber Mew is an experiment, much like Mewtwo was. In fact, if not for the bottom half of her body and the fact that she always carries a whip, she would look just like an armored Mewtwo. Her armor is electronic in nature, and apparently amplifies her psionic talents.
The bottom half of Cyber Mew is strange, as she is able to create a mini-whirlwind and carry the upper half of her body on that. She is not as powerful as either Steve or Mewtwo, though she does have similar attacks.
Meta Mew is a pre-evolution form of Cyber Mew. It mainly looks like a Mew with cybernetic parts. These parts show on the right side of her face, her left side, including arms and legs, and the tip of her tail.