Neesha, a Pokémon Trainer from Kanto, received an invitation to New Island seeking its legendary strongest Trainer. Facing storm-blocked ferries at Old Shore Wharf, she disregarded warnings from Officer Jenny and pier manager Miranda. Confident in her Dewgong's abilities, she used it to cross the treacherous sea.

Upon reaching New Island, she introduced herself and her team to Ash Ketchum and his companions. During the confrontation with Mewtwo, she battled cloned Pokémon. Neesha deployed her Blastoise, Shellshocker, against Mewtwo's cloned Blastoise. Shellshocker used Hydro Pump, but the clone countered with Rapid Spin, defeating it swiftly. Neesha attended to her injured Pokémon afterward. Mewtwo captured all present Pokémon, including Neesha's Dewgong, Shellshocker, Wigglytuff, Vileplume, Ninetales, and Rapidash, using specialized devices. These Pokémon were cloned, sparking conflict. Neesha witnessed Ash's intervention in the battle between Mewtwo and Mew, his temporary petrification, and revival. Mewtwo then erased the memories of all humans, including Neesha, regarding New Island before returning them to Old Shore Wharf.

In an alternate continuity depicted in "I Choose You!", Neesha battled Corey in the final round of a Pokémon League Conference. Her Blastoise used Ice Beam against Corey's Gengar, forcing a recall, and later engaged his Venusaur in an unresolved match; the scoreboard indicated she had at least five other Pokémon.

Her known Pokémon include Dewgong (used for sea transport), Shellshocker (Blastoise, knows Hydro Pump and Ice Beam across continuities), Wigglytuff, Vileplume, Ninetales, and Rapidash. Neesha maintains a calm, approachable demeanor with quiet confidence. Her resolve is evident in her decision to brave hazardous conditions for challenging battles.