The complete Pokemon GSC pokedex, part 1

Pokémon Name: Bayleef
Type: Grass
Classification: Leaf Pokemon
Pokédex Number: 153
Ability: Overgrow
Dream World ability: Leaf Guard
Useful Attacks: Magical Leaf
Location Found:
HG/SS: Starter Pokemon
D/P/P: Trade with HG/SS
B/W: Poke Transfer

The seeds around Chikorita's neck have sprouted, making way for Bayleef's increased power and size. It's almost identical to Ivysaur in terms of base stats.

Evolution: From Chikorita at 16, to Meganium at 32