Mew was the first pokemon ever. He was the creator of all attacks so he can use any he wants in battle. Later, Arceus made the pokemon and Mew gave each their moves. He has many cards and has been in many movies and some episodes. One of his most famed appearances was when he fought Mewtwo in the first movie "Mewtwo Strikes Back." He can also change forms into any pokemon he wants and he can teleport.
Mew full art

Here is the full art Mew card from the set Legendary Treasures