Meganium did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Meganium (Japanese: メガニウム Meganium) is a Grass-type Pokémon.
It evolves from Bayleef starting at level 32. It is the final form of Chikorita.
Meganium is a pale green, sauropod-like Pokémon with yellow eyes. It has two stamen-like protrusions sprouting from the top of its nose, each tipped with its own anther. These protrusions are shorter on the female. It has four feet, each of which have three toes. The leaves around its neck seem to have sprouted into a large pink flower with a yellow central pattern and white tips.
It is said that Meganium's petals can release an aroma that can soothe anyone that comes in contact with it and can calm aggressive feelings, and its breath has the power to revive dead grass and plants. Its powerful and soothing regenerative powers can even come about by being around it, giving those who stand near the impression of being in a clean and lush forest. Meganium tend to be a very docile species and has been portrayed as a peacemaker in the anime. Meganium can rarely be found living in grasslands.