Here's why:
* Red Rescue Team only has Pokémon from Generation 1. This means you can only find Pokémon from the original 151 Pokémon. Bulbasaur is from Generation 1, but he is not available in this game.
* The starter Pokémon are predetermined. When you start the game, you're given the choice of being either a Pikachu, Charmander, or Squirtle.
If you're looking for a Grass-type starter, your best bet is to choose Squirtle and then evolve it into Wartortle and eventually Blastoise.
Want to play with Bulbasaur? Try out Pokémon Mystery Dungeon: Explorers of Time, Darkness, or Sky! These games feature a wider range of Pokémon, including Bulbasaur, making them a great option for catching your favorite Grass-type starter.