In the Johto region, Ash was given a lost egg and was tasked with giving it to Professor Elm. He and Brock raised the egg which later hatched into a Larvitar. In Mother of All Battle, Ash and friends reached Mt. Silver where Larvitar's mother had given birth to it. They later spotted a Tyranitar, who turned out to be Larvitar's mother, that was being attacked by the Poacher Brothers. Once the Pokémon was saved, it was the proper time to hand Larvitar back to his mother. With that, Ash and his friends moved on.
Larvitar evolves into Pupitar when it reaches level 30, and then evolves into Tyranitar at level 55.