Pokémon Black and White 2/Completing the Pokédex

In Black and White 2, the Unova Pokédex contains a total of 301 Pokémon, the most of any regional Pokédex in the series (Not including SwSh). This makes completing the Pokédex more difficult than ever, but thankfully there are several ways that you can make achieving this task slightly easier. You'll have to use many different methods to be able to catch 'em all.

Catching Pokémon
Throughout your journey, you'll come across many Wild Pokémon which you can catch, which is how you will be obtaining the majority of the Pokémon in the Pokédex. Wild Pokémon can be encountered by walking in tall grass, walking through caves, walking in sand, surfing on water, and fishing. In order to successfully capture a Pokémon, you'll have to weaken it, but not too much so that it doesn't faint. The lower a Pokémon's HP, the higher the chance that you will successfully capture it using a Poké Ball. Between 10 and 15% is usually a good amount to lower it to. You can increase this chance by using specialized Poké Balls or afflicting certain status conditions onto your opponent, such as Sleep or Paralysis.

Phenomena
While on your adventure, you will come across certain kinds of phenomena: rustling grass, which appears in tall grass, dust clouds, which appear in caves, and rippling water, which appears on water, and can be surfed on or fished in. There is also a fourth type which only appears on Driftveil Drawbridge and Marvelous Bridge: flying Pokémon's shadows, which you can walk into. You will often find higher leveled or rarer Wild Pokémon in these than usual, but this is not guaranteed. Sometimes you may find regular Pokémon, or items such as Gems and Wings. There are some Pokémon, such as and, that can only be found through the use of phenomena.

Hidden Grottoes
Special Wild Pokémon can be found in Hidden Grottoes scattered around the Unova region, which are a new feature introduced in Black and White 2. For every 256 steps that you take, there is a 5% chance that something will appear in a Hidden Grotto, unless there is something in it already. This can be either an item or a Pokémon. All of the Pokémon that you encounter in a Hidden Grotto will have their Hidden abilities, which cannot be obtained through any other means except the Dream World. While some of the Pokémon found in Hidden Grottoes can also be attained through other methods, some of them must be found this way. Luckily, the majority of these aren't in the Unova Pokédex, so you can skip over them if you want.

Tips
While weakening Pokémon and using a Poké Ball is often enough to capture weaker Pokémon, you will probably have to do a little more to catch the stronger, rarer ones. Here are a few tips on how to do this:
 * Use specialized Poké Balls: While the basic Poké Ball will work in the early stages of the game, it becomes pretty much useless later on. As you progress through the game, you'll be able to purchase better ones, such as Great Balls or Ultra Balls, which have higher success rates. There are also Poké Balls which have specific effects, such as Quick Balls, which work best on the first turn of a battle. There are many other types of Poké Ball that you can find, so try using the one that is most suited for what you are trying to catch.
 * Use status conditions: Inflicting sleep or freeze onto your opponent will double your chances of a successful capture, while inflicting a burn, paralysis or poison will increase it by 50%. If you're having trouble catching a certain Pokémon, try using a Pokémon that can inflict any one of these status conditions, preferably sleep or freeze.
 * Use False Swipe: is a move that, when used correctly, makes catching Pokémon much, much easier. It always leaves a Pokémon with at least 1 HP. If you have difficultly catching a Pokémon without making it faint, consider using a Pokémon that knows False Swipe, or teach it to a member of your party. Because you can use TMs multiple times, simply get rid of False Swipe once you've captured the Pokémon you want, and have your Pokémon relearn it if you ever need to use it again.

Evolving Pokémon
Some Pokémon in the Unova Pokédex can't be encountered in the wild through any method, and must be acquired through evolving their more basic forms. This can be done through four methods: leveling them up to a certain level, leveling them up under certain conditions, using an evolutionary stone on them, or trading them. Evolved Pokémon tend to have higher stats than their previous forms, but also learn new moves slower.

Leveling up
Leveling up a Pokémon to a certain level is fairly simple, but can take a while. Whenever you defeat an opponent, your Pokémon will gain experience points, or EXP. After gaining enough EXP, the Pokémon will level up, and upon reaching a certain level, evolve. You can use this method to obtain Pokémon that can't be found in the wild, or are extremely rare.

To make leveling up an easier task, make use of held items such as the Lucky Egg, which boosts the amount of EXP a Pokémon gets, or the EXP Share, which gives whichever Pokémon that holds it a portion of the EXP earned in battle. If you find that facing wild Pokémon takes too long, try battling against wild, which can be found in rustling grass and yield more EXP than other Pokémon, or visit places such as Big Stadium or Small Court, where there are many Trainers that can be battled daily.

There are many Pokémon in the Unova Pokédex that don't evolve upon reaching a certain level. Instead, they evolve when they are leveled up while having high friendship with you. Four of these are baby Pokémon whose evolved forms can be found in the wild anyway, so raising their friendship and getting them to evolve is pretty pointless. They are, , and. In addition to this, certain Pokémon that evolve when they are leveled up while having high friendship can only do so at a certain time of the day. Budew and only evolve during the day, while  can evolve into either  or  if it is day or night, respectively.

Evolutionary stones
There are 9 evolutionary stones which you can use on Pokémon to cause them to evolve: the Fire Stone, the Water Stone, the Thunderstone, the Leaf Stone, the Moon Stone, the Sun Stone, the Shiny Stone, the Dusk Stone and the Dawn Stone. You will have to use all of these, with the exception of the Dawn Stone, in order to complete the Unova Dex. There is a total of 20 Pokémon in the Unova Pokédex that can be obtained when you use an evolutionary stone on their unevolved forms: 4 with the Fire Stone, 3 with the Water Stone, 2 with the Thunderstone, 1 with the Leaf Stone, 4 with the Moon Stone, 3 with the Sun Stone, 2 with the Shiny Stone and 1 with the Dusk Stone. Half of these can be caught in the wild (,, , , (White 2 only), ,  (Black 2 only),  (White 2 only),  and ), but are usually very rare and cannot be found until after you defeat the Elite Four.

Trading
Certain Pokémon in the Unova Pokédex can only be obtained if you trade their unevolved forms with other players. They are, , and. The latter two's unevolved forms, and, must be traded with each other in order for the evolutions to take place. In addition, there are some Pokémon that can only be obtained if you trade their unevolved forms while holding certain items. They are (Metal Coat),  (Electirizer, White 2 only) and  (Magmarizer, Black 2 only). Out of all of these Pokémon, only one (Steelix) is available to be caught in the wild, so unless you can find somebody else to trade with, you cannot obtain any of these Pokémon.

Other Methods
While leveling up, having high friendship, using stones and trading are some of the most common methods by which Pokémon can evolve, there are a couple more methods that are a little trickier.
 * Some Pokémon can only evolve if they are leveled up while knowing a certain move.
 * can only evolve into if it is leveled up while knowing.
 * , and  can only evolve into,  and , respectively, if they are leveled up while knowing.
 * Some Pokémon can only evolve if they are leveled up in a certain area.
 * can only evolve into if it is leveled up in the same area as a Mossy Rock, which can be found in Pinwheel Forest.
 * Likewise, it can only evolve into if it is leveled up in the same are as an Icy Rock, which can be found in a cavern in Twist Mountain.
 * and can only evolve into  and, respectively, if they are leveled up in Chargestone Cave.
 * Some Pokémon can only evolve if they are leveled up while holding a certain item.
 * can only evolve into if it is leveled up at night while holding a Razor Fang.
 * can only evolve into if it is leveled up at night while holding a Razor Claw.
 * can only evolve into if it is leveled up while a  is also in the party.
 * can only evolve into if it is female and reaches level 21. While they are a lot more common, male Combee don't evolve at all.

Trading Pokémon
If you're having difficulty catching a certain Pokémon, you can always see of somebody else you know is willing to trade it to you. You can perform a trade by selecting it under the IR menu on your C-Gear, or by visiting the union room on the top floor of any Pokémon Center. Alternatively, if you have an internet connection, you can visit the GTS (Global Trade Station) in any Pokémon Center to trade with people around the world. The drawback to doing this, however, is that you can only search for Pokémon that you've already seen. You will have to trade in order to complete the Unova Pokédex, as no matter which version you are playing, there will be some Pokémon that you cannot obtain. For a full list, see the list of Version-exclusive Pokémon.

Trading Pokémon has its benefits. Any Pokémon that you receive in a trade will gain 1.5× more experience than usual, while Pokémon that originated from a foreign language game gain 1.7× more. As mentioned earlier, some Pokémon only evolve when they are traded. If you trade a Pokémon away, you will not lose its Pokédex entry, meaning that both you and the person that you traded it to will have the Pokémon registered in your Pokédex. Another useful aspect of trading is that you can give items to your Pokémon to hold, which will also be transferred to the other player. This can be used for sending messages using Mail, or more useful things such as giving Master Balls, evolutionary stones or other rare items to other players. Unfortunately, TMs cannot be given to Pokémon to hold.

On the other hand, there are also some drawbacks to trading Pokémon. Firstly, high leveled traded Pokémon will only obey you if you have enough Gym Badges, so you can't just trade over powerful Pokémon at the beginning of the game and expect to do well. Furthermore, any Pokémon's friendship value is instantly reset upon trading. Even if you trade a Pokémon back to its original game, it will have lost all of its friendship points with its original Trainer. Lastly, you are forbidden from changing the nickname of any Pokémon that is traded from another game.

There are also some in-game trades which you can perform with NPCs. These trades work exactly the same as trades with other players, except that the trade will be for a specific Pokémon, and you cannot get your Pokémon back once you have traded it away. Make sure that you never give a held item to a Pokémon that you are going to trade away to an NPC, especially if it is rare one, as it will be lost forever. Two characters that have many potential trades are Yancy and Curtis, who you will encounter about halfway through the game.

Breeding Pokémon
The final method by which you can obtain Pokémon is breeding.