I think Cresselia is one of those Pokemon whose very existence is threatened by Opposing Tyranitar. The mere presence of a Tyranitar spells doom for Cresselia. Sand Stream ruins it's only recovery, Pursuit wears it down, DD variants set up on it, CB outright kills it, and it can't do anything back. When you're a liability against one of the Top 5 Pokemon in the Game, you're dead weight more often than not. I think Cresselia should have like 50/105 offenses so it's not so helpless. Doesn't is look like a pure Special Attacker?
It's really kind of pathetic though how Psychic went from the best type in the game to (arguably) the worst type. Poison and Ice are horrible types for offense and defense respectively, but Psychic just sucks in general.