srk1214
My main thing is that, while Tailwind is a great support move, it is completely countered by Trick Room. A single use of Tailwind leaves you very, very open to TR setting, making you open as fuck to a quick turnaround. I'll be posting a set this round too to address this issue, but I figured I'd give my thoughts on Tailwind setting.
You can usually tell from Team Preview if the opponent is running Trick Room or not. Semi-TR is harder but can suspected too. Having Tailwind doesn't mean you will set it up against a TR team, and it would help you against every other team - it's not necessary, but it's helpful.
Bisharp is also great against TR teams. Though I do agree that extra insurance against TR teams would help.
My point was that Tailwind shouldn't be dismissed because it works badly against TR teams. My post doesn't really involve TR Cress.
Besides, Cress should always be suspected on having TR unless suspected otherwise - think twice before setting up Tailwind up against a team with Cress.
You can usually tell from Team Preview if the opponent is running Trick Room or not. Semi-TR is harder but can suspected too.
You forgot Expert Belt...160+ SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Garchomp: 316-372 (88.2 - 103.9%) -- 25% chance to OHKO
160+ SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Latios: 126-150 (41.7 - 49.6%) -- guaranteed 3HKO
It's not as strong as you say it is. If you're going offensive, you need more SpAtk and less Defense to get the KOs you want. But even 252+ doesn't guarantee everything. 252+ SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Garchomp: 344-408 (96 - 113.9%) -- 75% chance to OHKO.
If you want Trick Room and enough SpAtk to OHKO the things you want to kill, you're better off with Mew, Slowbro/king, or even Mesprit. Reuniclus and Meloetta are powerful too though they lack Ice Beam.
That's not to say that it's a bad set. But the calcs are off.