Mew

Mew is a Psychic-type Mythical Pokémon from the Kanto region. It is currently only Pokémon of Kanto region that is unavailable to obtain.

Trivia

 * On August, 2016 Mew's attacks - Hurricane and Moonblast were replaced with Blizzard, which has higher DPS.
 * On March 26, 2018, Niantic announced a new Research tasks game mechanic which hints at the possibility of obtaining Mew.