It's a trapper set, not a boosting set. Thought that would be obvious. And who the fuck tries to curse on an obvious whirlwind. In theory, this thing basically kills everything that doesn't 2HKO it if it gets trapped.
Assume nothing's obvious unless you blatantly state it. Also, your trapping's not gonna do much when you're most likely slower than your opponent, taking a hit, cursing which does tons of damage to yourself, and then taking another hit immediately the turn after before you can Roost. Regardless of how the argument's changed and how the set's supposed to be used, it's bad and a waste of a Decidueye. And also, "this thing basically kills everything that doesn't 2HKO it if it gets trapped." The argument works in theory but doesn't in practice. You're gonna be slower than 95% of the Offensive threats in the meta some way or another, and so the only way to get a free trap is to force a switch, Shackle the mon that switched in, tank a hit, curse, tank the next hit, and then roost spam until they die.
Sounds good. And then you remember that NOBODY IS GONNA SWITCH IN A MON IF IT CAN'T 2HKO YOU. So your set falls flat on its face in practice. I like the idea but it just doesn't work. You're better off trapping a mon on the switch (Which most likely beats you), and guarantee a free switch into the respective mon on your team that beats the switchin. It's why Tyranitar, Weavile, Magnezone, and Dugtrio are such good partners with Decidueye in the first place. Anyways, the only time this set could POSSIBLY work is against Stall without a phaser (Good luck finding one of those).
Sidenote: It seems a LOT of you are forgetting that Decidueye's trapping potential isn't like any other mons. The thing it's most comparable to is Pursuit and that's ONLY because it's a move. That's the key point to remember. It's a MOVE. This isn't Arena Trap. This isn't Shadow Tag (God bless). This isn't Magnet Pull. This is a move that hits the opponent and forces them to stay in. It's a move that needs to be used for utility, pivoting, and momentum shifting. Not single mon executions. Remember the limits it has and you'll use Decidueye a lot more efficiently.