Neesha is one of four Pokémon Trainers who managed to brave Mewtwo's storm to get to New Island by riding her Dewgong.
Neesha battled Mewtwo's clone Blastoise using her own Blastoise called Shellshocker. The battle ended quickly after Mewtwo's Blastoise managed to spin through Shellshocker's Hydro Pump and managed to strike it.