Three years ago, shortly after the crowning and subsequent retirement of Champion Brendan, Hoenn was battered by an enormous number of meteors. This disaster, known as the Hoenn Catastrophe, greatly transformed Hoenn's landscape, turning much of the southern end into a barren wasteland and destroying the Battle Frontier, among other things. This also had a profound change on the wildlife, driving many species to extinction. More strangely, new species of Pokémon, known as Meteoric Pokémon, began appearing everywhere. At the forefront were three very powerful and evil Pokémon... The story begins as you move into Littleroot Town, and are asked by Professor Birch to complete the Pokédex in order to document all the new species. You meet Birch's niece (or nephew), April (or Gordon), as well as Billy, the little brother of the current League Champion, Wally. In addition, the Petalburg Gym Leader, Romero, has a little brother himself, who keeps crossing your path. His name is Mosmero, and he's quite the strange one. Despite being an adult, he travels the region performing all kinds of pranks. Less