Blastoise, the Shellfish Pokémon. The evolved form of Wartortle. Blastoise’s strength lies in its power, rather than its speed. Its shell is like armor and the attacks from the hydro cannons on its back are virtually unstoppable.
– Ash’s Pokedex
Rawr, Blastoise is the mascot Pokemon for Pokemon Blue and is featured on the boxart. It is quite popular, due to being the first fully evolved water starter. It’s one of my favourite Water starters. It’s based on a tortoise with cannons on its back, which makes it using Hydro Cannon pretty awesome.
In the anime, Ash never evolved his Squirtle, so we don’t see it much. But Gary Oak has a Blastoise, which evolved from the Squirtle he got as a starter. Strangely, it’s the only fully evolved water starter in the anime owned by a main character (not counting Barry and his Empoleon).
Stat-wise, it has good Defense and Sp Defense, and lower Attack/Sp Attack. It has about equal Attack and Sp Attack, and can learn both physical (like Aqua Tail and Earthquake) and special (Hydro Pump, Surf, Ice Beam) attacks, so it can be a mixed attacker.