Foul play is actually pretty anti meta dont go knocking it too hard. I run sash zam with psyshock, shadowball, dazzling gleam and focuz blast. But, if you have a physical booster not named cloyster like haxorus for example. Foul play does more damage when had is at +2 than dazzling gleam.
+2 0- Atk Alakazam Foul Play vs. 120 HP / 0 Def Haxorus: 272-321 (84.2 - 99.3%) -- 75% chance to OHKO after Stealth Rock
Its actually great lure while you maintain the sash. I think they were expecting a psyshock switch in like mega aggron which foul play wouldve hit harder. As for psychic and psyshock, both have merits. Maybe not so much on the same set, but it allows yoy to hit both the defensive and sp def aide almost equally as hard.
Never really thought if it that way. Then again, it was running Psyshock. & Psychic on the same set. :P