IGN : varicelle / variation / varilebogoss

Answer 1 : mesprit :3

Answer 2 : after some search on bulbapedia i ain't found any folk tales about the lake trio but a regular tales that say, if you look into the eyes of uxie, you'll lose all knowledge, if you touch mesprit, you'll lost all your emotions (i saw during 3 days) and last of all don't try to hurt / harm azelf, or you'll lost all your will (for 5 days i saw) and so you'll grow immobile in entirely.

IGN : Eric66

Answer 1 :Uxie

Answer 2 : They come from the same egg created by Arceus

OR

They hatched from an egg that was created by Arceus

IGN :Wheeloftime

Answer 1 :Uxie

Answer 2 :From the same egg that create by "Arceus"

IGN : Atipmon

Answer 1 : Azelf

Answer 2 : The Lake Trio represents/inspired from the Triforce from Legend of Zelda

IGN : giratinassc1

Answer 1 : Uxie

Answer 2 : They hatched from an egg that was created by Arceus

IGN : Mecta

Answer 1 : Uxie

Answer 2 : Those Trio Lake [ Uxie / Mespirit / Azelf ] came from Arceus, when Arceus created the universe it created those Trio . Three of them were born from the same egg.

Skfrodo :

Answer 1 : Mesprit

Answer 2 : The myth says that if you encounter the lake trio, you will lose knowledge, emotion, and will harm azelf by looking into its eyes. It continues to state that if any of the guardians are harmed, the person who encounters them will become completely immobile.

IGN :hahahaka

Answer 1 :Mesprit

Answer 2 :If you look at them into the eyes, in but an instant, you'll have no recollection of who you are.

If you touch them, in but three short days, all emotions will drain away.

If you harm them, in a scant five days, you will grow immobile in entirety.

IGN : tuyetytran

Answer 1 : Azelf

Answer 2 : From the Triforce from Legend of Zelda

IGN :Blitzkrieg

Answer 1 :Mesprit

Answer 2 : If you look into Uxie's eyes, you will suffer a loss of knowledge, if you touch Mesprit, your emotions will be drained and if you harm Azelf, you will lose your will.