Tailwind is a Speed-boosting Flying-type move. Tailwind doubles the Speed stat of the user and all other Pokémon in the user's party for four turns
As of 1.0.4, it can be taught by the Buff Move Tutor of Tsukinami Village Hotel for four Yellow Shards. In 1.0.3, it could be taught by the Ultimate Move Tutor of Tsukinami Village for four of each color shard.
Pokémon that learn Tailwind
By leveling up
Via Move Tutor