Pokémon Mystery Dungeon: Explorers of Sky Unlockables

After you beat the game, there are two different forms of evolution that you need to earn.
UnlockableHow to unlock
Normal EvolutionJust beat the main game, meaning the final boss, and the Master of all things Bad.
Starter/Partner EvolutionTo get this one, you need to defeat Darkrai, Recruit Palkia, and unlock Marine Resort. Congrats, you can now evolve you're Partner and Starter Pokemon.