From Bulbapedia, the community-driven Pokémon encyclopedia.
Foothill Town (Japanese: フタバタウン Futaba Town) is a small anime-exclusive town in Hoenn that was visited by Ash and his friends in the episode Delcatty Got Your Tongue?. It is very close to Verdanturf Town.
While on their way to Verdanturf Town for May's next Contest, Ash and his friends were confronted by Team Rocket. They fought with them, but during the fight May's Skitty got injured by the smoke of Ash's Torkoal. They defeated Team Rocket and hurried themselves to find the nearest Pokémon Center to get help for Skitty.
They hoped to find one in Foothill Town but heard from a local woman that the town doesn't have a Pokémon Center. They did however find out that there is a Pokémon Clinic at the edge of the town. They got there and found out that the Clinic was operated by Dr. Abby, a former Hoenn Grand Festival winner. Dr. Abby managed to heal Skitty and later helped her to learn Blizzard.
Coincidentally, the town shares its Japanese name with Twinleaf Town, the starting town in Sinnoh.