Ruby - "Shedinja's hard body doesn't move - not even a twitch. In fact, its body appears to be merely a hollow shell. It is believed that this Pokémon will steal the spirit of anyone peering into its hollow body from its back."
Sapphire - "Shedinja is a peculiar Pokémon. It seems to appear unsought in a Poké Ball after a Nincada evolves. This bizarre Pokémon is entirely immobile - IT DOESN'T EVEN BREATHE."
D/P/Pt - "A discarded bug shell that came to life. Peering into the crack on its back is said to steal one's spirit."
Diamond - "A Pokémon that was formed by 108 spirits. It is bound to a fissure in an Odd Keystone"
Pearl - "It was bound to a fissure in an Odd Keystone as punishment for misdeeds 500 years ago."
Platinum - "Its constant mischief and misdeeds resulted in it being bound to an Odd Keystone by a mysterious spell."
3. Gary's Raticate
Its only speculation but; In Gen 1 you fight Gary and his Raticate on S.S. Anne. After that Gary never uses this Raticate again, and when you see him in Lavender Town he asks you if you know what its like to have one of your Pokémon die?
OMG YOU KILLED RATICATE!!! YOU BASTARD!!!
There is something about the dead cold stare of a Magikarp that really creeps me out. You know its just thinking about all the awful things that has happened to it in battle and in the wild. Its just thinking about level 20 and all the evil it can do.