I think you might need a bit more experience before you start writing analyses.
The first set I guess isn't terrible... You don't specify what move the second spread beats Heracross with. Since the Psychic attacks affect different stats and have different base power this is important! You also can't put two EV spreads on the same set. You put zero discussion into what the different coverage moves do, or why you would ever use any of them.
The Dual Screen set is a bit messy too. Your description basically consists of "yay screens" "maybe don't run one of them if you want more moves". You're going to need to add a lot more than that. No discussion on the advantages of the other moves, or team support needed. No discussion of potentially running Speed to outrun a particular Taunting wall or anything.
The Grab Bag set is a mess. You literally just looked up every move Cresselia can learn that might be vaguely useful and put it on a set. People go to Smogon to find out the best sets a Pokemon can run, not every single set.
As for other options, Choice Specs and Calm Mind play completely differently, I don't see how they're at all comparable. The writing style is quite informal, and I really doubt you actually looked up what "KOs" the Specs set can use. You really do allude to the biggest problem with Cresselia: "Why not use Mew?" (Or Uxie, who has a better support movepool).
Your counters section needs a lot of work. Heracross is a start, though it is weak to Psychic. You suggest that the best counter for Cresselia is something that takes super-effective damage from its STAB attack. A zero investment Psyshock is a guaranteed 2HKO on 252 / 120 / 136 Roserade. Meanwhile, once you determine there's no threat of status, any number of Dark types can come in for free. Bronzong can usually set up whatever it wants all over Cresselia, but he gets no mention. Sableye is also going to create a lot of problems, being able to priority Sub on any unboosted special attack and Taunt you to stop you from doing anything.
Finally, saying "it gets that, right?" when it would have taken you maybe 4 seconds of work to find that out just illustrates the little work you've put into this...
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