What Pokemon are not in Pokemon LeafGreen?

All Pokemon from Kanto, Johto, and Hoenn can be obtained in LeafGreen. Ekans, Arbok, Oddish, Gloom, Vileplume, Bellossem, Psyduck, Golduck, Growlithe, Arcanine, Shelder, Cloyster, Scyther, Scizor, Elekid, Electabuzz, Wooper, Quagsire, Murkrow, Qwilfish, Delibird, Skarmory, and Deoxys (Attack Form) must be traded from FireRed. Some legendaries can only be obtained from events. Other Pokemon like all of the starters must also be traded over.