In this sequel the pokedex has 300 Pokemon, some of which are native to other regions but were added to the sequel, with 154 new Pokemon.
This game introduced the Oval Charm, which increases the chance of an egg being found at the Pokemon Day Care, and the Shiny Charm, which increases the chance of encountering shiny Pokemon.
In this game if you complete the Unova pokedex you will have the chance to capture a level 60 shiny Haxorus.