From Bulbapedia, the community-driven Pokémon encyclopedia.
Nene (Japanese: 少女ネネ Young Nene) is a minor recurring character who first appeared in Why Not Give Me a Z-Ring Sometime?. In the Japanese version, she and Piko refer to Acerola as "Big Sis".
Nene is close friends with Piko. They asked Acerola to read them a story, which she did. They later watched as Acerola was captured by a Gengar.
Nene reappeared in Tough Guy Trials! at Acerola's house alongside Piko.