Sandshrew's Locker

On their way to Hearthome City, Ash & Co. meet Mira who offers to give them a shortcut using her Abra's Teleport. However, when they fail to arrive at Hearthome, Mira asks Ash & Co. for a favour, to help find a pendant that was lost at the bottom of sea. Reluctantly, Ash & Co. agree and go underwater. However, the pendant is found out to be a Pokémon's Pokéball, and is in some ruins protected by a Gyarados. Will Ash & Co. get the Pokéball and get to Hearthome in the end?