While giving their Pokémon a medical checkup after a storm, Liko and Mollie find what appears to be a solitary Tandemaus, a Pokémon that normally comes in pairs. The Tandemaus brings them to a tunnel blocked off by a fallen tree, where they quickly retrieve its companion. When the Tandemaus continues to cry out for others deeper in the tunnel, Liko follows it along with Hatenna and finds two smaller counterparts to Tandemaus, revealing the group to be the Pokémon’s evolved form, a Maushold family of four. Hatenna learns Heal Pulse to heal the injured Maushold, which remain aboard the Brave Olivine thereafter. (Source: Wikipedia)