Bulbasaur is a quadruped, reptilian creature that somewhat resembles a toad or a young dinosaur with a spotted blue-green hide. It has three white toes or claws growing out of its four legs, and its eyes are a bright red. The most notable feature of this Pokémon is the onion-like bulb on its back, which grows from a seed planted on its back by its mother at birth. Unlike the parasitic tochukaso mushrooms growing on the back of Paras, which eventually take over its body as it evolves into Parasect, Bulbasaur's bulb shares a symbiotic relationship that is beneficial for both. This allows Bulbasaur to get an enhanced boost of energy from the sun during the day and the bulb to remain growing and strong at night. The bulb also contains many seeds from which it draws nutrients.
Bulbasaur is the only unevolved dual type starter Pokémon.
Bulbasaur is the first Pokémon in the National Pokédex order. By default, this also makes it the first Grass type, Poison type, dual-type Pokémon, unevolved Pokémon, and starter Pokémon in National Pokédex order.
Since in Generation I, the Bug type was super-effective against Poison-type Pokémon, Bulbasaur was also the first Pokémon in National Pokédex order with a double weakness (to Bug type). Due to Generation II's changes to type effectiveness, this "honor" has since been taken by Charizard, which has a double weakness to Rock-type moves.