From Bulbapedia, the community-driven Pokémon encyclopedia.

Gen	Game
I	Red	Blue	Yellow	Red (Ja)	Green	Back
II	Gold	Silver	Crystal			Back
III	Ruby	Sapphire	Emerald	FireRed	LeafGreen	Back
			Image:Spr 3e 001 s.gif
IV	Diamond	Pearl	Platinum			Back
			Image:Spr 4p 001.png
			Image:Spr 4p 001 s.png

For other sprites and images, please see Bulbasaur images on Bulbagarden Archives.