How to meet and catch the three Lake Guardians, Uxie, Mesprit and Azelf
Meeting the Lake Guardians
During your adventure, you will cross paths with the 3 Lake Guardians several times without being able to catch them. When you meet Dialga/Palkia at Spear Pillar, you will see them again. It is after your battle with the Legendary Pokémon of your version that you will finally be able to catch Uxie, Mesprit and Azelf!
Meeting and Catching Uxie at Lake Acuity
Uxie is the first of the Lake Guardian trio. Its lake is Lake Acuity, located at the Acuity Lakefront. Follow the path leading north to find the lake. Use HM Surf to find the Acuity Cavern. This is where you will find the first of the three Lake Guardians: Uxie.
Uxie
Uxie Shiny Uxie
Known as the “being of knowledge.” It is said that its gaze has the power to erase memories.
Type : 
Weaknesses : 
Height : 0.3 m
Weight : 0.3 kg
Gender : unknown
Category : Knowledge
Ability : Levitate
Moves : Imprison / Extrasensory / Amnesia / Psychic
Meeting and Catching Azelf at Lake Valor
Azelf is the second Lake Guardian. Its lake is Lake Valor, so head to the Valor Lakefront and follow the path west. Then use HM Surf to find the Valor Cavern. This is where you will find the second of the three Lake Guardians: Azelf.
Azelf
Azelf Shiny Azelf
Known as the “being of willpower.” It sleeps at the bottom of a lake to keep the world in balance.
Type :
Weaknesses :
Height : 0.3 m
Weight : 0.3 kg
Gender : unknown
Category : Willpower
Ability : Levitate
Moves : Imprison / Extrasensory / Nasty Plot / Psychic
Meeting and Catching Mesprit at Lake Verity
Mesprit is the third and last Lake Guardian. Its lake is Lake Verity, so head to the Verity Lakefront and follow the path west. Then use HM Surf to find the Verity Cavern. This is where you will find the last of the three Lake Guardians: Mesprit.
Chasing Mesprit
The first time you interact with it, Mesprit runs away. Don’t panic! The conversation with Professor Rowan explains that you will have to track it down across the Sinnoh region to find it again.
Open the “Marking Map” app on your Pokétch to track the Pokémon!
Mesprit
Mesprit Shiny Mesprit
Known as the “being of emotion.” It teaches humans the beauty of sadness, pain and joy.
Type :
Weaknesses :
Height : 0.3 m
Weight : 0.3 kg
Gender : unknown
Category : Emotion
Ability : Levitate
Moves : Psychic / Charm / Extrasensory / Imprison
Did you knock out the Pokémon but still want to catch them?
Make them reappear! To do so, go back to their respective caverns (for Uxie and Azelf), and to the routes for Mesprit. (Don’t forget that you need to have beaten the Pokémon League.)
—
Sprites courtesy of Poképédia.
