Additional Moves: Shadow Ball
Additional Items: Ghostium-Z, Life Orb, Choice Specs
Notes: Filter can be used if you have a dedicated Chatot switch in since Defiant / Competitive pokemon deter Silvally from removing hazards or phasing out using Parting Shot.
Mr.Mime can afford to drop Dazzling Gleam if you require coverage against specific faster threats since you already hit the dragons (Hakamo-o and Silvally Dragon) hard enough and threaten them with your typing and ability.
Due to lacking Nasty Plot, the Healing Wish set is walled by bulky psychics including Recycle Grumpig and Musharna and should not be played to beat these threats without trick as this set is for revenge and offensive utility.
NeN (Z-Shadow Ball) sets can forfeit running coverage for probopass to always beat psychic types that don't mind dazzling gleam like Bronzor, Metang, and CM Swoobat while still nabbing the ohko against Mawile.