To bring back an earlier nomination that got no feedback, I'd like to repost it. :P
to B+ rank
Cresselia isn't very bad right now. Being able to check MegaGross, Mega Altaria, some Keldeo, Azumarill, Lati twins, and others is pretty good when the metagame revolves around them. She also has access to TWave and Toxic to cripple things like Slowbro, Keldeo, Latis, MegaGross, and the aforementioned threats above. And that bulk is just amazing. 120/120/130 is amazing solid, being able to tank hits on both sides of the spectrum. She also has access to Ice Beam to take out or scare out things like Landorus-T locked into EQ, Landorus-I lacking Knock Off(even then it doesn't 2HKO), etc. Levitate isn't a bad ability, being able to beat Garchomp, Landorus-T, Excadrill, etc is nothing to sneeze at. And of course, she has a Knock Off weakness which hurts a lot. And her recovery isn't very reliable, but she can wall a lot of things if done properly.
Cresselia isn't very bad right now. Being able to check MegaGross, Mega Altaria, some Keldeo, Azumarill, Lati twins, and others is pretty good when the metagame revolves around them. She also has access to TWave and Toxic to cripple things like Slowbro, Keldeo, Latis, MegaGross, and the aforementioned threats above. And that bulk is just amazing. 120/120/130 is amazing solid, being able to tank hits on both sides of the spectrum. She also has access to Ice Beam to take out or scare out things like Landorus-T locked into EQ, Landorus-I lacking Knock Off(even then it doesn't 2HKO), etc. Levitate isn't a bad ability, being able to beat Garchomp, Landorus-T, Excadrill, etc is nothing to sneeze at. And of course, she has a Knock Off weakness which hurts a lot. And her recovery isn't very reliable, but she can wall a lot of things if done properly.
-0 Atk Life Orb Landorus Knock Off (97.5 BP) vs. 252 HP / 252+ Def Cresselia: 140-166 (31.5 - 37.3%) -- 85.8% chance to 3HKO
0 SpA Cresselia Ice Beam vs. 0 HP / 0- SpD Landorus: 272-324 (85.2 - 101.5%) -- 12.5% chance to OHKO
+1 252+ Atk Pixilate Mega Altaria Return vs. 252 HP / 252+ Def Cresselia: 202-238 (45.4 - 53.6%) -- 1.2% chance to 2HKO after Leftovers recovery
252 Atk Tough Claws Mega Metagross Meteor Mash vs. 252 HP / 252+ Def Cresselia: 135-160 (30.4 - 36%) -- guaranteed 4HKO after Leftovers recovery
252 SpA Life Orb Latios Draco Meteor vs. 252 HP / 4 SpD Cresselia: 220-259 (49.5 - 58.3%) -- 64.5% chance to 2HKO after Leftovers recovery
252 SpA Choice Specs Keldeo Hydro Pump vs. 252 HP / 4 SpD Cresselia: 213-252 (47.9 - 56.7%) -- 35.9% chance to 2HKO after Leftovers recovery
252+ Atk Choice Band Huge Power Azumarill Play Rough vs. 252 HP / 252+ Def Cresselia: 169-201 (38 - 45.2%) -- guaranteed 3HKO after Leftovers recovery
+2 252 Atk Garchomp Outrage vs. 252 HP / 252+ Def Cresselia: 249-294 (56 - 66.2%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Life Orb Excadrill Iron Head vs. 252 HP / 252+ Def Cresselia: 122-146 (27.4 - 32.8%) -- 81.3% chance to 4HKO after Leftovers recovery
0 SpA Cresselia Ice Beam vs. 0 HP / 0- SpD Landorus: 272-324 (85.2 - 101.5%) -- 12.5% chance to OHKO
+1 252+ Atk Pixilate Mega Altaria Return vs. 252 HP / 252+ Def Cresselia: 202-238 (45.4 - 53.6%) -- 1.2% chance to 2HKO after Leftovers recovery
252 Atk Tough Claws Mega Metagross Meteor Mash vs. 252 HP / 252+ Def Cresselia: 135-160 (30.4 - 36%) -- guaranteed 4HKO after Leftovers recovery
252 SpA Life Orb Latios Draco Meteor vs. 252 HP / 4 SpD Cresselia: 220-259 (49.5 - 58.3%) -- 64.5% chance to 2HKO after Leftovers recovery
252 SpA Choice Specs Keldeo Hydro Pump vs. 252 HP / 4 SpD Cresselia: 213-252 (47.9 - 56.7%) -- 35.9% chance to 2HKO after Leftovers recovery
252+ Atk Choice Band Huge Power Azumarill Play Rough vs. 252 HP / 252+ Def Cresselia: 169-201 (38 - 45.2%) -- guaranteed 3HKO after Leftovers recovery
+2 252 Atk Garchomp Outrage vs. 252 HP / 252+ Def Cresselia: 249-294 (56 - 66.2%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Life Orb Excadrill Iron Head vs. 252 HP / 252+ Def Cresselia: 122-146 (27.4 - 32.8%) -- 81.3% chance to 4HKO after Leftovers recovery