Neesha is one of the Pokémon Trainers that appeared in Pokémon the First Movie: Mewtwo Strikes Back. Like the other trainers, she received an invitation to meet the "best Pokémon trainer in the world" at New Island.

Because of a storm, Officer Jenny would not let them travel, so she and other trainers used their Pokémon to cross the sea. She used her Dewgong to do so.

Pokémon

As seen in the Movie:

Pokémon	Information
Blastoise	She calls it Shell-Shocker. It fought against the clone made by Mewtwo, but fainted and was captured by Mewtwo.
Ninetales	Like the others, it was captured, cloned and liberated by Ash.
Wigglytuff	Like the others, it was captured, cloned and liberated by Ash.
Vileplume	Like the others, it was captured, cloned and liberated by Ash.
Rapidash	Like the others, it was captured, cloned and liberated by Ash.
Dewgong	Used to cross the sea and reach New Island. Like the others, it was captured, cloned and liberated by Ash.