Legendary Pokémon

Like all Pokémon games, there's a myriad of Legendary Pokémon to collect. Some are available throughout Sinnoh while others require you to go through Ramanas Park. Like prior Pokémon games, they will return if you defeat them without capture and then beat the Elite Four

Dialga & Palkia

Location: Spear Pillar

You will encounter Dialga or Palkia, depending on your version, as you progress through the story. As Team Galactic's plan unfolds through the Sinnoh region, you will make chase to Spear Pillar where Cyrus will unleash his plans to create a new world. However, when you defeat him, Uxie, Mesprit and Azelf will appear and free Dialga/Palkia, and it will then want to battle you.

Dialga
Level 47
OT:Yours
ID:Yours
Ability:Pressure
??? Nature.
Date of Receiving
Spear Pillar. Level Met: 47
Ancient Power
Slash
Flash Cannon
Roar of Time
Palkia
Level 47
OT:Yours
ID:Yours
Ability:Pressure
??? Nature.
Date of Receiving
Spear Pillar. Level Met: 47
Ancient Power
Slash
Aqua Ring
Spacial Rend
Dialga in Pokémon Brilliant Diamond & Shining Pearl

Uxie

Location: Lake Acuity

After preventing the cataclysm at the Spear Pillar, you'll now be able to visit the lakes and encounter the Pokémon. In the cave at Lake Acuity, you will find the Pokémon Uxie.

Uxie
Level 50
OT:Yours
ID:Yours
Ability:Levitate
??? Nature.
Date of Receiving
Lake Acuity. Level Met: 50
Imprison
Extrasensory
Amnesia
Psychic
Uxie in Pokémon Brilliant Diamond & Shining Pearl

Mesprit

Location: Lake Verity, Sinnoh

After preventing the cataclysm at the Spear Pillar, you'll now be able to visit the lakes and encounter the Pokémon. In the cave at Lake Verity, you will find the Pokémon Mesprit but it won't battle you but rather will roam through Sinnoh to be found, being tracked by the Marking Map app on the Pokétch. Its IVs, Shiny status and Nature are determined when it leaves Lake Verity.

Mesprit
Level 50
OT:Yours
ID:Yours
Ability:Levitate
??? Nature.
Date of Receiving
??. Level Met: 50
Imprison
Extrasensory
Charm
Psychic
Mesprit in Pokémon Brilliant Diamond & Shining Pearl

Azelf

Location: Lake Valor

After preventing the cataclysm at the Spear Pillar, you'll now be able to visit the lakes and encounter the Pokémon. In the cave at Lake Valor, you will find the Pokémon Azelf.

Azelf
Level 50
OT:Yours
ID:Yours
Ability:Levitate
??? Nature.
Date of Receiving
Lake Valor. Level Met: 50
Imprison
Extrasensory
Nasty Plot
Psychic
Azelf in Pokémon Brilliant Diamond & Shining Pearl

Heatran

Location: Stark Mountain

After you get the National Dex and go to the Fight Area, you will meet Buck who says about a treasure that is to be found in Stark Mountain. When you go to Stark Mountain, you will help Buck get to the final room where he will take the Magma Stone. Return to the Survival Area and his grandfather will tell him that the Magma Stone needs to be there else the volcano will erupt so Buck goes and puts it back. If you go back to the deepest room in Stark Mountain, you will find the Legendary Pokémon Heatran.

Heatran
Level 70
OT:Yours
ID:Yours
Ability:Flash Fire
??? Nature.
Date of Receiving
Stark Mountain. Level Met: 70
Metal Sound
Earth Power
Heat Wave
Stone Edge
Heatran in Pokémon Brilliant Diamond & Shining Pearl

Regigigas

Location: Snowpoint Temple

After you get the National Dex, you'll be given access to Snowpoint Temple in the north of Snowpoint City. At the bottom floor in the middle of the ice puzzle is Regigigas, but it is sound asleep. If you bring Regirock, Regice and Registeel caught from Ramanas Park to it, it will awaken offering you the chance to catch it..

Regigigas
Level 70
OT:Yours
ID:Yours
Ability:Slow Start
??? Nature.
Date of Receiving
Snowpoint Temple. Level Met: 70
Wide Guard
Zen Headbutt
Heavy Slam
Hammer Arm
Regigigas in Pokémon Brilliant Diamond & Shining Pearl

Giratina

Location: Turnback Cave

After you get the National Dex, you'll be given access to the Sendoff Spring, a mysterious fourth lake to the east of Route 214. In this lake you will fin Turnback Cave. This cave is a winding maze that gives you instructions on the pillar. Your task is to get to the end in 30 rooms or less. The pillar gives you a specific number and that number equates to the clockwise exit you need to take on entering each room. If you follow the instructions, you will be find Giratina in its Altered Forme.

Giratina
Level 70
OT:Yours
ID:Yours
Ability:Pressure
??? Nature.
Date of Receiving
Turnback Cave. Level Met: 70
Shadow Force
Pain Split
Aura Sphere
Dragon Claw
Giratina in Pokémon Brilliant Diamond & Shining Pearl

Cresselia

Location: Fullmoon Island, Roaming Sinnoh

After you get the National Dex, you'll be told by the Sailor in Canalave that he has lost the feel for sailing since his child got sick. If you speak to the child, you will learn that he is stuck in a nightmare. You will learn that the Lunar Feather will cause him to wake up so you go with the Sailor to Fullmoon Island. There you will find Cresselia. It won't battle you but will run away and roam Sinnoh, being tracked by the Pokétch Marking Map app. The Lunar Feather will remain. Its IVs, Shiny status and Nature are determined when it leaves Fullmoon Island.

Cresselia
Level 50
OT:Yours
ID:Yours
Ability:Levitate
??? Nature.
Date of Receiving
???. Level Met: 50
Slash
Psycho Cut
Moonlight
Safeguard
Cresselia in Pokémon Brilliant Diamond & Shining Pearl