Miltank appeared in the episode A Goldenrod Opportunity where she battled Ash Ketchum in a Gym battle. With a powerful Rollout attack, Miltank was able to take out all of Ash's Pokémon, easily thereby defeating him.
Miltank also appeared in A Dairy Tale Ending where Ash found out that the reason why Miltank was so strong was because it trained by using Rollout to roll up and down a steep hill.
Team Rocket then appeared to steal all of their Pokémon in a giant barrel-shaped mecha which rolled on the hill. Ash used Totodile to create holes on the ground to slow the mecha down and then used Pikachu to blast them off again. He realized he could use the same strategy against Whitney.
He used Cyndaquil to tire Miltank out, Totodile's Water Gun attack to dig trenches to divert Miltank's Rollout, and subsequently had Pikachu knock her out. With this win Ash earned the Plain Badge.
Miltank was later seen in Lyra's fantasy in Bagged Then Tagged!, along Whitney, as well as Morty and his Gengar, when Lyra mentioned that her next Gym battle would be against either of those two Trainers.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In the games
Miltank is also Whitney's main Pokémon in the games. It appears in Gold, Silver, Crystal, HeartGold, and SoulSilver, as well as in both rounds of Pokémon Stadium 2. This Miltank is widely regarded as one of the most difficult Pokémon to defeat in a Gym, owing to its high stats, powerful attacks, ability to incapacitate male opponents with Attract, ability to hit Ghost types with Stomp and Body Slam due to its ability Scrappy, and ability to recover with Milk Drink and Rest, especially since it holds a Lum Berry to cure the sleep that Rest causes.
