Ash's Larvitar

Ash recieved an egg that he was supposed to deliver to Professor Elm in Johto (the Master Quest season.) It hatched into Larvitar (Japanese: ヨーギラス Yogiras) while Ash had it and became very close to Ash and his Pikachu, but Hardened if anybody else approached it. Its life in the egg that was the reason it was traumatized and mistrustful was revealed in the episode Address Unown when Ash and friends are teleported to another dimension, they eventually find an egg with a dark crystal-like thorn in it. They are shown a flashback, hear a child's voice crying that he was scared and calling for his mother and then figured out that it was Larvitar's voice. Poachers kidnapped it in its egg and fired at its mother several times, leaving a scar on her body. The thorns start covering everything while Ash calls for Larvitar. The three manage to get through to Larvitar and the thorns- and its fear- disappear and they return to the real world.

The poachers are stopped at Mt. Silver in the episode Mother of All Battles and Larvitar is reunited with its mother Tyranitar.

Ash's Larvitar- like all of his old Pokemon- appeared in the Spurt! (スパート！) opening, along with its mother.