Ash's Blastoise (Aura)

Ash's Wartortle was Ash Calem Ketchum's sixth Pokémon.

Kanto
Squirtle was abandoned by his trainer and left to roam the streets of Vermilion City, playing pranks everywhere he went. When Ash and his friends arrived in Vermilion City, they spied Squirtle spraying graffiti against a wall.

Ash sensed that Squirtle had a good heart, and he would be proven right as he helped Pikachu, Bulbasaur and Charmander against Team Rocket aboard the S.S. Anne. After that, Squirtle joined Ash and his team.

Personality and characteristics
Wartortle is one of Ash's most trustworthy Pokémon, but is by no means perfect. Compared especially with his closest friend, the very serious Ivysaur, he comes across as immature and mischievous, particularly during his time as a Squirtle alone, where he would commit various pranks and so on. However through his travels with Ash, he matured considerably.

Mature or not, Wartortle is shown to prefer wearing sunglasses occasionally.