Blastoise is a large, bipedal turtle-like Pokémon. Its body is blue and is mostly hidden by its tough, brown shell. This shell has a pale yellow underside and a white ridge encircling its arms and separating the upper and lower halves. Two powerful water cannons reside in the top sides of its shell. These cannons can be extended or withdrawn and can be used to assist in high-speed charges. Blastoise's head has triangular ears that are black on the inside, small brown eyes, and a cream-colored lower jaw. Its arms are thick and striated with three claws on each hand. Its feet have three claws on the front and one on the back. It has a stubby tail.
As Mega Blastoise, it develops two smaller shells over its arms, each with their own water cannon. The two cannons on its back are replaced by a single, central water cannon of greater size. This cannon extends forward over Mega Blastoise's head and is said to have a blast range of over 6 miles (10 km). Small ridges develop over its now-red eyes and extend to its ears. The larger cannon can retract into its shell. The ears angle slightly backward and there is a small point on its chin.
Neesha, a Trainer who went to New Island in Mewtwo Strikes Back, had a Blastoise nicknamed Shellshocker. It fought with Mewtwo's cloned Blastoise and lost. It was taken away from her by one of Mewtwo's special Poké Balls but was liberated by Ash along with the other confiscated Pokémon. Along with Ash's Charizard and Corey's Venusaur, they were the only confiscated Pokémon not to be cloned: this could be because Mewtwo didn't need more than one copy of each Pokémon and it already had their clones. Neesha's Blastoise appeared in an alternate timeline of the main series that was introduced in I Choose You!, where it was seen battling Corey's Venusaur; it is unknown if it holds the same nickname in that timeline.
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 attacks from the hydro cannons on its back are virtually unstoppable.
Squirtle has two older sisters who are Blastoise. Their names are Kameko and Kamemi and they appear in The Five Sisters of Squirtle. Kameko is the oldest of all of Squirtle's siblings, with Kamemi as the second-oldest.
A Blastoise was fantasied along with the other fully evolved Kanto Starters in Chinchou in Charge, where the Pokémon Association Chairman of Kanto and Johto explains to Bill and Janine the special privilege of entering the finals unconditionally after collecting the badges.
In the Pokemon Golden Boys manga
A Blastoise appears in The Truth About The Mysterious Whirl Islands!!. It had ruled over the island for a century before turning violent. At Slowking's request, Gold defeats it, destroying Slowking's Cave in the process. The Blastoise later appears at the end of GB20 along with Slowking and Lugia.
When released from a Poké Ball, Blastoise will use Hydro Pump in one direction. Each Pump moves Blastoise backwards slightly making it a danger to those fighting behind it as well. Blastoise's trophy also refers to Blastoise as the 'Definitive Water Type'.
"Blastoise is the next evolutionary step after Wartortle. The thick jets of water they shoot from the cannons on their backs are strong enough to cut through steel plating. When in danger, they hide inside their armored shells. Blastoise is so popular among Trainers that it's considered the definitive Water-type."
NA:On a hot summer day, it's great to cool off by playing in a sprinkler. Don't look to Blastoise as a replacement, though—those water jets on its back are extremely powerful and would send you flying. In fact, Blastoise itself is so huge so it doesn't get blown away when it fires. Speaking of fires, Blastoise is better than a fire truck at putting them out!
PAL:Tempted to have a Blastoise hose the mud off your bike? Well, don't. The water jets from its rocket cannons might look perfect for that, but they'd just blast your bike into oblivion. In fact, the reason Blastoise grow so big and heavy is so they don't get blown away themselves. If your house is on fire, though, feel free to get a Blastoise to help!
NA: Some species of Pokémon living in Kalos have the ability to Mega Evolve, and here's one! Mega Blastoise is a bit bigger than Blastoise, and instead of two cannons on its shell, it has one huge cannon. This may seem like a downgrade, but wait–there are two on its arms! This math is easy: three is better than two.
PAL: Some species of Pokémon living in Kalos have the ability to Mega Evolve, and here's one! Mega Blastoise is a bit bigger than Blastoise, and instead of two cannons on its shell, it has one huge cannon. This may seem like a downgrade, but wait - there are two on its arms, too! Basic arithmetic: three is better than two.