How to Level Up Fast in Pokemon White and Black

Place the Pokemon you wish to level up in the first slot of your party, making it the primary Pokemon in battle. If you have obtained the Lucky Egg item in the game, give it to the primary Pokemon to hold. This item doubles the experience points gained by the item's holder in battle.

Find an area with grass where wild Pokemon can attack you. If you have already finished the game, the best spot is on Route 14, just outside of the White Forest. Make sure that your primary Pokemon is at least level 50 if you are planning to use this spot to level up. If your Pokemon is below level 50, you may still use this location to train it, but you will need another Pokemon that is at least level 50.

Get on your bicycle and ride up and down (or side to side) near the area of grass until one of the patches of grass starts to rustle. This may take anywhere from a few seconds to a couple of minutes.

Use a repel and then walk into the rustling patch of grass. The repel will prevent you from being attacked by another wild Pokemon before you can reach the rustling patch of grass; if you are attacked by another Pokemon before you reach the rustling grass, you will have to repeat Step 3 after the battle is over. The Pokemon in the rustling patch of grass will usually be a wild Audino, which will give you massive amounts of experience points when killed.

Fight and kill the wild Audino, then watch as your Pokemon gains thousands of experience points after just one battle. If you are training a low-level Pokemon (under level 50) at the grass areas on Route 14, you will need to use the following fighting method: Make sure the weak Pokemon you want to level up is the primary Pokemon and is holding the Lucky Egg. Also make sure that you have a level-50 or higher Pokemon in your party. As soon as the battle starts, switch from your weak Pokemon to your strong Pokemon. Continue the battle and win with the strong Pokemon. When the battle ends, the strong Pokemon will earn some experience, but since the weak Pokemon was also exposed to the battle at the start, it will gain massive amounts of experience points, especially since it is holding the Lucky Egg.

Repeat the process as much as desired. Note that if your Pokemon reach the level 75 mark, you should now fight the Pokemon League's Elite Four trainers in order to efficiently continue leveling up your Pokemon.