One of the core objectives in any Pokémon game is to 'catch 'em all' and complete your Pokédex. In Pokémon Yellow, this means catching 150 unique Pokémon (Mew is the 151st and requires special events or glitches).
- Wild Encounters: Explore every route, cave, and body of water. Different areas have different wild Pokémon. Use 'Surf' and 'Good Rod'/'Super Rod' to find Water-type Pokémon.
- Evolution: Many Pokémon evolve by leveling up, using Evolution Stones (e.g., Fire Stone, Water Stone), or by trading.
- Trading: Some Pokémon, like Kadabra, Machoke, Graveler, and Haunter, only evolve when traded. You'll need to link up with another Game Boy player.
- Version Exclusives: Pokémon Yellow has some unique wild Pokémon compared to Red/Blue (e.g., Mankey, Growlithe, Ekans, Meowth, Vulpix are wild in Yellow). However, some Pokémon from Red/Blue are not found in Yellow and require trading (e.g., Jynx, Electabuzz, Magmar).
- Fossils: Revive the Dome or Helix Fossil from Mt. Moon at the Cinnabar Island Pokémon Lab.
- Safari Zone: A unique area in Fuchsia City where you can catch rare Pokémon like Chansey, Scyther, and Pinsir.
Completing the Pokédex is a long-term goal that will take you across the entire Kanto region and beyond.