Alola Lapras

Ability: Mystical Spring - Causes all Water type moves used by the Pokémon to become a dual attack: Fairy Type and Water Fairy Type, also receive a 30% boost.

It is said that a herd of Lapras took refuge in a cave for a big thunderstorm that was raging in the seas of Alola, the entrance of the cave collapsed with a loud bang and desperate Lapras tried to flee deeper into the depths of the cave to the point of doom, as they could not feed some were about to die, but for his surprise they found a beautiful oasis surrounded by ice where sunlight barely reaches and a group of Comfeys living there helped them with their healing abilities and fed them with blue flowers that only grew when they were dancing in the moonlight, spent many decades until Lapras managed to find an exit of that labyrinthine iceberg, but for the astonishment of the natives the Lapras that came out from these frozen caves acquired a different appearance as a result to adapt to this mystical place.

(Take the reference of the oasis in the middle of the ice from ATLA and the Northern Water Tribe  )