In accordance of Pokemon Month, I present to you why Ghost Pokemon trump all (mainly because all of them want to eat your soul):
Duskull: He's the boogeyman mothers tell their kids about to behave, and if they don't, he'll steal them away in the middle of the night... to eat their soul. Loves the sound of crying children.
Dusclops: Its body is hollow, and if you look inside, it'll suck your soul in.
Drifloon: It floats around, causing to children to mistake it for a balloon, except when they grab it, he takes them away and eats their souls.
Shedinja: It's the dead shell of a Ninjask, but don't stare into the hole in its back, or your soul's gone forever.
Chandelure: If its flames consume you, it burns your soul away.
Gengar: Hides as your shadow, to steal your soul. (and eat it)
Haunter: Saps away your soul by licking you. It LICKS your soul off.
Ghastly: It wraps its opponent in its gas-like body, slowly weakening its prey by poisoning it through the skin.
Misdreavus: It eats your fears for nutrition.
Anybody got a counterargument?