"Gotta catch 'em all" has been the slogan for the Pokemon franchise. Thus, when the original Japanese Generation II was released, they introduced 100 new Pokemons to catch. The Pokedex also includes the Generation I Pokemons, which gives a total of 251 unique Pokemons. On top of that, they introduced Shiny variants for the Pokemon, which appears extremely rarely and is a prized item for collectors. For the less extreme fans, they (though somewhat misguidedly) added Unown, a Pokemon shaped based on the English alphabet with 26 different forms (in that generation) to collect. To accommodate for players who wishes to fill their PC with all unique Pokemons (excluding Shiny Pokemons) and Unown forms, they also increased the PC Pokemon storage capacity from 240 to 280, just barely enough to fit them.