Pokemon Kanto Expansion Pak Game Boy (Also works on GBC/GBA) 

Purchase Options: (1) Game Only [No Case] OR (2) Custom Case + Game

You've finally been granted your Pokemon trainer's license. Now, it's time to head out to become the world's greatest Pokemon Trainer. It's going to take all you've got to collect all 251 Pokemon in this enormous world.

- A Brand New PokeDex, with 251 Pokemon including beta and regional variants
- Now choose between Red and Green to start your new journey through Kanto
- A total of five starter Pokemon to choose from including Pikachu and Eevee
- Seek out the Galarian Birds and solve the Paradoxical Enigma
- Running shoes / fast Surf (press B)
- Move deleter
- Move reminder
- Tradeback move tutor
- Trade-to-self NPC
- An elaborate postgame (highlights for me are a boss rush gauntlet, gym leader and E4 rematches, a battle facility and secret legendary encounters)
- An open world format allowing you to fight the gyms in any order you want