Just to show the insane bulk of this thing, here is a set with deoxys after a swords dance (on that random chance it was baton passed), and after furfrou got a cotton guard.
Psycho Boost: 81.63 - 96.61%Ice Beam: 37 - 43.78%Superpower: 50.84 - 59.88%ExtremeSpeed: 16.94 - 20.05%
252 SpA Deoxys-A Psycho Boost vs. 252 HP / 90 SpD (custom): 289-342 (81.63 - 96.61%) -- guaranteed 2HKO
(289, 294, 297, 300, 303, 307, 310, 313, 318, 321, 324, 327, 331, 334, 337, 342)