Legendary Pokemon - Pokemon Black 2 and White 2 Pokemon Black 2 and White 2: Legendary Pokemon
Cobalion Pokemon B2W2 Sprite
Cobalion
Lv. 45		 Location: Route 13

Cobalion in first seen in Route 6. It can be caught in Route 13. It's waiting out in the open of the route.
Terrakion Pokemon B2W2 Sprite
Terrakion
Lv. 45		 Location: Route 22

Terrakion is out in the open in Route 22. Akuroma will give you an item once you interact with Terrakion.
Virizion Pokemon B2W2 Sprite
Virizion
Lv. 45		 Location: Route 11

Virizion stands in the middle of Route 11.
Reshiram Pokemon B2W2 Sprite
Reshiram
Lv. 70
White Exclusive		 Zekrom Pokemon B2W2 Sprite
Zekrom
Lv. 70
Black Exclusive		 Location: Dragonspiral Tower

After beating the game, N can be found in the ruins of his castle. He will battle you. After he is defeated, Reshiram/Zekrom will turn into stone. This is your chance to capture it.
Kyurem Pokemon B2W2 Sprite
Kyurem
Lv. 70		 Location: Giant Chasm

After capturing N's Reshiram/Zekrom, return to the Giant Chasm. Kyurem will leave behind the item needed to change it's form once it's captured.
Latias Pokemon B2W2 Sprite
Latias
Lv. 68
White Exclusive		 Latios Pokemon B2W2 Sprite
Latios
Lv. 68
Black Exclusive		 Location: Dreamyard

The Dreamyard becomes accessible after beating the game. Either Latias or Latios will approach you when entering. It will then flee further into the Dreamyard where you must track it down.
Uxie Pokemon B2W2 Sprite
Uxie
Lv. 35		 Location: Nacrene Museum

Visit the Heart Cave after beating the game. Professor Juniper will see Uxie, Mesprit, and Azelf traveling away. This event makes Uxie appear in front of the Nacrene Museum after standing on a specific spot nearby.
Mesprit Pokemon B2W2 Sprite
Mesprit
Lv. 35		 Location: Celestial Tower

Visit the Heart Cave after beating the game. Professor Juniper will see Uxie, Mesprit, and Azelf traveling away. This event makes Mesprit appear at the top of the Celestial Tower after standing on a specific spot nearby.
Azelf Pokemon B2W2 Sprite
Azelf
Lv. 35		 Location: Route 23

Visit the Heart Cave after beating the game. Professor Juniper will see Uxie, Mesprit, and Azelf traveling away. This event makes Azelf appear on the west side of Route 23 after standing on a specific spot nearby.
Regirock Pokemon B2W2 Sprite
Regirock
Lv. 65		 Location: Underground Ruins

Regirock is in the Underground Ruins located in the Clay Road. There is a tile puzzle that must be solved before catching Regirock. Afterwards, you acquire either the Steel Key (Black 2) or the Iceberg Key (White 2) which can be used to catch Registeel or Regice.
Regice Pokemon B2W2 Sprite
Regice
Lv. 65
White Exclusive		 Registeel Pokemon B2W2 Sprite
Registeel
Lv. 65
Black Exclusive		 Location: Underground Ruins

Regice can be caught in White 2 by using the Iceberg Key. Registeel can be caught in Black 2 by using the Steel Key. Take either key to where Regirock was captured.

Both Pokemon can be caught in either version by using the Unova Link to trade for the opposite key.
Regigigas Pokemon B2W2 Sprite
Regigigas
Lv. 68		 Location: Twist Mountain

After capturing Regirock, Regice, and Registeel, bring all three Pokemon to the basement of Twist Mountain. This will allow you to battle Regigigas.
Cresselia Pokemon B2W2 Sprite
Cresselia
Lv. 68		 Location: Marvelous Bridge

The Lunar Wing can be found in a house in Yamaji Town. Bring the Lunar Wing to Marvelous Bridge for Cresselia to appear.
Heatran Pokemon B2W2 Sprite
Heatran
Lv. 68		 Location: Rebirth Mountain

Find the Magma Stone in Route 18 and bring it to the cave in Rebirth Moutain that Bianca talks about earlier in the game.