Venustoise

Venustoise is an infamous Pokémon that debuted on episode 20 of the Pokémon anime. It was created by the components of a Blastoise and Venusaur, when a Gastly was confronted by Ash's Squirtle and Bulbasaur. The Gastly fused Blastoise and Venusaur together, thus making this Pokémon Fusion. It spawned an interest of people making their own Pokémon Fusions. It has become very popular since its appearance.

Venustoise, as well as the method resulting in its creation, are a parody of the Fusion Technique from the Dragon Ball franchise.