One of the Pokémon is Uxie, the being of knowledge. Uxie is able to wipe memory clean and create illusions. Uxie looks like he has a yellow hat, his body is gray, and he has two tails. Uxie lives at Fog Bound Lake where he guards a time gear.
The next triplet is Mesprit, the girl Pokémon that clones. Mesprit is the being of emotions. She guards her gear at an underground lake. She has four purple things coming out of her head, a gray body, and two tails.
And finally, we have Avelf, the protector of yet another time gear. This one is at Crystal Lake. He or she, we don't know his gender, has the power to make crystals in the blink of an eye. He has a blue head, a gray body, and two tails.
In the game, Pokémon Mystery Dungeon: Explorer of Time and Darkness, you have to fight something at each lake. At Fog Bound Lake, you have to fight an illusion of Grawden. In the Underground Lake, you fight Mesprit. At Crystal Lake, you fight Growviule. All in all, Pokémon Mystery Dungeon: Explorer of Time and Darkness is a really entertaining GameBoy DS game.