Condition: Game only. Tested/Works
Pokémon Yellow features several enhancements and changes. Including the below-mentioned inclusion of Pikachu as the only available Pokémon to start with, Pikachu is given both a voice and a personality unique from other Pokémon. It follows the player on the overworld, and can be examined by speaking to it. While it initially has an indifferent opinion of the player, it can grow to love or hate him based on the player's actions; leveling up will keep Pikachu happy, while fainting frequently will make it unhappy.