Narissa is a beginning Pokémon Trainer who owns two Ditto: one with regular coloration and one that is Shiny. She also owns an orange-colored Pokédex. According to her, she is called the "Rumbler" where she comes from.
Upon meeting Ash and his friends, Narissa seemed incredibly full of herself, calling Ash a "newb" Trainer before proudly announcing that she had been a Trainer for one month. She additionally claimed that she had no Badges because the Gym Leaders would run in fear of her Ditto. Also, when she was about to participate with her Ditto in a Double Battle against a Trainer's Cubone and Marowak, Narissa had them both take the form of a passing Zapdos, causing the Trainer and his Pokémon to run in fear.
Despite this tough and confident facade, however, Narissa is actually quite meek and self-conscious, as well as being a crybaby. She cosplays as Flint of the SinnohElite Four, whom she greatly admires, in order to help her feel more sure of herself.
Narissa's first Ditto, nicknamed Ditto 1 (Japanese: メタモン１号Metamon Ichigō), is of normal coloration, and first appeared to the gang when it transformed into Pikachu, Piplup, Gible, and Togekiss and caused mischief until Narissa turned up. Ditto was later used in battle against Pikachu, however despite being able to use Pikachu's powerful moves (like Iron Tail and Volt Tackle), it was easily defeated. Team Rocket later attempted to steal both Narissa's Ditto, however they escaped and teamed up with Ash's Pikachu and sent Team Rocket blasting off with a triple-Thunderbolt.
Narissa also owns a Shiny Ditto, nicknamed Ditto 2 (Japanese: メタモン２号Metamon Nigō). After joining its regular counterpart in causing mischief, Ash battled the Shiny Ditto with Infernape. In turn, Ditto transformed into an Infernape itself. After trading a series of Mach Punches, the round ended in Ash's favor. Later, the Shiny Ditto helped Ash his friends foil another Team Rocket scheme.
She is somewhat similar to Duplica, having two Ditto (with one of them being somewhat special) and cosplaying.
She, along with Wilhomena, Temacu, Natalie, Lucy, Lizabeth, Holly, and Autumn, is one of the few girls to have shown some feelings for Brock. Narissa, however, quickly got over these feelings once she witnessed Brock falling in love with a passing Trainer and once again declared Flint as the one she most admires.