Purple

Nikki first met Purple when he was a Nidoran(B), she used him very often in the Rock Tunnel, so once she was out of the Rock Tunnel, he evolved into Nidorino. She took great care of him and used him in the trainer battles she had. She had two moon stones and gave one to him. So he evolved into Nidoking.

He evolved into Nidorino, after battling in Rock Tunnel. He evolved into Nidoking when Nikki gave him a moon stone.