Roxanne is proficient in discerning a Trainer's inner capabilities with Pokémon, and uses this skill to determine whether a Trainer will be a strong battler. She is also very intellectual, as shown when she conducts a test for all would-be contenders for a Gym battle.
Roxanne is identical in appearance to her game counterpart.
Ruby and Sapphire Chapter
Roxanne appears at the Rustboro City Gym before Sapphire, who is surprised that the Gym Leader is conducting a test. She then hands a test paper to Sapphire, who begrudgingly is forced to take the examination. Roxanne informs Sapphire that she cannot face all of the Trainers who want to battle her, so she holds this examination to find the best Trainer to fight against. Later, Roxanne is shocked when Sapphire scores a perfect 100 in the test, asking whether she is related to Professor Birch. Sapphire confirms this, to which Roxanne accepts her Gym leader challenge. Roxanne outlines the rules for their battle, as the two Trainers release their Pokémon. When Sapphire's Aron attacks Roxanne's Nosepass with Metal Claw, it blocks with Harden. Realising that she cannot win with Rono, Sapphire attempts to switch her Pokémon out, to which Roxanne outlines that her Nosepass' ability prevents the opposing Trainer from withdrawing their Pokémon.
As the battle progresses, Roxanne is able to gain the upper hand, due to her Nosepass' ability. When Sapphire collapses underneath a pile of broken rocks, Roxanne states that she has lost, since her Rono is unable to battle. However, Rono emerges from the rubble and takes Nosepass off guard. Roxanne is surprised when she hears Sapphire explain how she bested Nosepass, through use of compass bearings. In honour of Sapphire's achievements, Roxanne presents her with the Stone Badge for defeating her. Later, Roxanne answers the call from Flannery for all Gym Leaders to assemble at Fortree City. Roxanne then arrives via her Graveler at Fortree City to attend the Gym Leader Conference alongside Brawly and Wattson.
As the meeting adjourns, Flannery informs the Gym Leaders that Team Aqua is directly responsible for the attack on Mt. Chimney, to which Roxanne asks whether Professor Cosmo was among those present at Mt. Chimney. Flannery confirms this, prompting Roxanne to announce her support for Team Aqua alongside Brawly and Wallace. This causes dissension between the attending Gym Leaders, as Norman announces that he does not support either team, much to Roxanne and the other's surprise. Norman begins to leave the Tree Tower, as Roxanne comments upon his sheer arrogant nature. Flannery and Winona explain that their forces are insufficient to deal with the mounting threat, and suggest that they call upon the assistance of powerful Pokémon Trainers, which is lauded by Roxanne. She states that such Trainers would only get in their way.
Later, when Winona brings Sapphire to Tree Tower, Roxanne and the other Gym Leaders approve of her decision to rally the Trainer's support. Later, when Groudon sets a heat wave upon Fortree City, Roxanne and the other Gym Leaders are aghast at the damage it have caused. When Roxanne, Brawly and Wallace attempt to head closer to Maxie and Archie's location, they are stopped in their tracks by the admins of Team Magma, The Three Fires. Roxanne then faces off against Courtney, whilst Brawly and Wallace fight against Mack and Wallace respectively. During their fight, Roxanne is able to use her Nosepass effectively against Courtney's Ninetales, but when the Magma Admin threatens to kill the innocent civilians, Roxanne cedes defeat to her.
Later, Roxanne is present when Ruby and Sapphire return to the Ba.Goon airship, and congratulates them upon their victory.