Platinum caught Lopunny sometime prior to Striking Out Snover, and was her first capture after starting her journey to Mt. Coronet. She was first seen in To and Fro with Froslass, participating in Platinum's Gym battle against Candice and her Abomasnow. Lopunny initially struggled due to Platinum's hesitancy since they had never battled before, but she soon shook it off and used Lopunny's agility and dance like movements to defeat Abomasnow. Lopunny then went up against Froslass and was immediately pinned down to prevent her from using the same strategy and was defeated. Before being defeated though, Platinum had Lopunny use Healing Wish in order to bring Rapidash back to full health, allowing Platinum to win the battle.
In Shorting Out Electivire, Lopunny was Platinum's first choice in her battle against Volkner and called out against Elekid. Lopunny fired a barrage of Focus Blasts but ended up missing and getting hit by Focus Punch. Although Volkner thought the battle was over, Lopunny used her speed to sneak up behind Elekid and use Dizzy Punch, giving Platinum the first win.
In Getting the Drop on Gallade II, Lopunny participated in Platinum's Battle Castle challenge. Lopunny is picked as her last resort against Darach due to Empoleon and Rapidash being close to defeat. She first went up against his Houndoom and almost took it out with one hit, but Houndoom endured thanks to its Focus Sash. Houndoom then countered with Fire Fang, but Platinum switched into Empoleon before the attack could hit. Lopunny was later sent out to battle against Darach's Gallade. Due to the type disadvantage and the damage taken from the battle before, Lopunny was easily outmaneuvered and took a direct hit from Night Slash. Barely standing, Lopunny managed to crawl over to Gallade and land a weak Dizzy Punch before fainting. Darach laughed at her weakness, but soon found out that Gallade was inflicted with Lopunny's Cute CharmAbility and confused by Dizzy Punch. This allowed Empoleon to easily defeat him, giving Platinum the win.
In Exit Empoleon, Lopunny fought in Platinum's Battle Arcade challenge. During the battle against Dahlia, Platinum and Dahlia had to switch Pokémon due to the roulette, meaning Lopunny and Platinum's other Pokémon were forced to fight against their Trainer. Although both sides were reluctant at first, both Platinum and her Pokémon manage to fight at their full strength, which eventually ended with Platinum as the victor.
Lopunny is a powerful and agile battler, being able to dance around her opponents with ease. Despite being powerful, Platinum often uses her to help the rest of her team fight, by either inflicting status conditions to opponents or healing her teammates. Lopunny has a strong connection with her Trainer and was the most reluctant of her Pokémon to fight her during the Battle Arcade match.