Once all her Pokémon were defeated, Whitney sent Miltank in the Gym match against Ash. Cyndaquil attempted to attack with Tackle, but got bashed into the wall by Miltank's Rollout. After both Pokémon repeated their attacks, Cyndaquil got defeated. Ash sent Totodile in the battle, who used Water Gun, but the attack wasn't able to stop Rollout. As Ash tried to think of a strategy, his Totodile got defeated. For his final Pokémon, Ash sent Pikachu, who tried to electrocute Miltank with Thunderbolt. It proved to be useless, as Miltank resisted the attack and defeated Pikachu, even when he used Agility, causing Ash to lose the Gym match.
Team Rocket, who stole some of the Miltank Dairy products, tried to retreat. However, Whitney's Miltank blasted them away with Rollout. After spending some time at the dairy, Whitney went to train Miltank, to improve her speed. Team Rocket arrived once more and stole Miltank and Pikachu, both of which were rescued by Ash's Cyndaquil and Totodile. Once Team Rocket were defeated by Pikachu again, Ash requested a rematch from Whitney, who sent Miltank against Ash's three Pokémon. Cyndaquil tried tackling Miltank, but failed and got hit by Miltank's Rollout attack. Ash swapped Cyndaquil with Totodile, who used Water Gun on the ground to make ditches. It went on Miltank, but the latter use Rollout on the side and hit the former with the same attack. For his final Pokémon, Ash swapped Totodile with Pikachu, who used Agility to boost his speed and hide in a ditch. Miltank continued using Rollout, but when it flew across the ditch, Pikachu tackled her from under the ditch and defeated Miltank with a quick Thunderbolt. Whitney, who assured Ash Miltank would be fine, gave him a Plain Badge for this victory.
When Team Rocket stole Ash's badges, the latter was searching for the them. He also remembered his battles with the Johto Gym Leaders, including Whitney and her Miltank, as Ash and his Pokémon won those badges with hard effort.