Ivysaur is the evolved form of Bulbasaur. In the RPG series, Bulbasaur evolves into Ivysaur at level 16, and then evolves into Venusaur at level 32.
Ivysaur appears as a moderately large, blue, squat, quadrupedal saurian with the plant on its back now in the form of a pink bud and large green leaves. The bulb formerly on its back has grown and partially bloomed both to exposure from sunlight and apparently from drawing energy from Ivysaur's own body, which also gets stronger when it absorbs sunlight. The budding flower is heavy enough that Ivysaur appears to lose the ability to stand on its hind legs, but its four legs and trunk grow thick and strong from the weight of the flower, even as a quadruped. If it starts spending more time lying in the sunlight, it is a sign that the bud will bloom into a large flower soon, which would be heralded by the bud giving off a sweet, pleasant aroma and the specie's evolution into its final form, Venusaur.
A Seed Pokémon that is the evolved form of Bulbasaur. It has a flower bulb on its back, the weight of which has made it develop strong legs and hips. If the blossom gets too big, the Pokémon can't stand on two legs alone. At a certain level, it evolves into Venusaur. When this happens, the bulb absorbs nutrients and blossoms into a large-petaled flower.