Darkrai

Darkrai is the primary antagonist of Pokemon Mystery Dungeon: Explorers of Sky/Darkness/Time.

Overview
Darkrai caused the Planet's Paralysis in the future, and tried to cause it in present time, but failed to due to your partner and you stopping it. Darkrai also disguised himself as Cresselia and tried to get rid of your partner and yourself. He is the true one to cause ruin to the fabric of space, and tricks Palkia into thinking it's you. At the end, he waits at Dark Crater to challenge you. Once you beat him, we will try to escape but Palkia hits him with Spacial Rend whilst traveling into the portal, destroying his memory.

Ability
Darkai is around level 55-60 and he IQ type I his known moves are Dark Void, Disable, Hypnosis, and Nightmare. He is really strong because if you fall asleep you will be damaged due to his ability Bad Dreams

Recruit
If you get certain items (ex. Lost Loot), you can find Darkrai in various dungeons and possibly recruit him. It is unknown if this is another Darkrai or not.