List of Pokémon by index number (Generation III)
In each Pokémon game of Generation III, all Pokémon have an unseen index number used to identify them in the game's ROM. The majority of them are in their National Pokédex order, in fact, all Pokémon from 001 to 251, inclusive, are in the same position as they are in the National Pokédex.
List of Pokémon by index number