Instructions
Turn on your Nintendo DS, and start a new game of "Pokemon." You will be prompted to select your gender and name your character.
Leave your house and head into the tall grass to trigger a conversation with the Professor.
Pick one of the three starter Pokemon. Each generation has a Fire-type, a Water-type and a Grass-type starter Pokemon to choose from. In "Pokemon Black" and "White," your choices are Tepig, Oshawott and Snivy. Your two rivals will each pick one of the remaining starters. After picking a Pokemon, Professor Juniper will give you your Pokedex and send you on your way.
Leave the first town, heading into the tall grass. Wild Pokemon appear in tall grass, so walk around in the grass to encounter and battle them. Seeing a Pokemon will add it to your Pokedex, and catching it will provide you with additional information about the Pokemon.
Go from town to town, challenging the various gym leaders and progressing through the story. Along your way, make sure to explore the tall grass and take your time heading through caves.
Head for any shaking patches of grass, swirling areas of dust or dark spots of water you see along your way, since these hide rarer Pokemon than are usually found in that area.
Battle every trainer you see along the way. Some will challenge you from afar, while others will wait until you speak to them, so be sure to talk to everyone you see on your journey. Different trainers use different Pokemon, and battling them will help you add to your Pokedex.
Defeat the Elite Four and complete the main storyline with Team Plasma to receive the National Dex. Once you've gotten the National Dex, you'll be able to find and capture Pokemon from previous generations in the wild.
Buy plenty of Pokeballs when you enter a new town so you will always be ready to catch wild Pokemon while traveling between towns.
Capture as many Pokemon as you can and help them evolve. Different Pokemon evolve in different ways. Some need to be traded, while others need to have items used on them. Still others evolve just by leveling up, or by achieving a certain amount of happiness.
Trade for the Pokemon not available in your version. Different versions of Pokemon have different Pokemon available, and you will not be able to catch them all without trading.
Head to Route 15 and visit the Poke Transfer Lab. If you have a second Nintendo DS available, you can use the Poke Transfer Lab to send Pokemon from the fourth generation Pokemon titles -- including "Diamond," "Pearl," "HeartGold," "SoulSilver" and "Platinum" -- to your copy of "Pokemon Black" or "White."