You’ll need “Strength” to push Boulders and reach it. From the Pokémon Center, go straight down then straight right. Inside, use Surf again and you’ll finally reach it by the end of the lagoon.
Move ahead and use Surf until you see another cavern.
Enter the cavern, move straight, and go down the ladder you’ll see. From the entrance, head straight to the lake and climb up the big waterfalls. You’ll need “Surf” and “Waterfall” to get to it. TM02 (Dragon Claw) – Found deep inside Meteor Falls.
Pokémon OR/AS - Nintendo (Fair Use) TM (Technical Machine) Locations