To answer your initial question, Flash Cannon<Iron Head, as tue set that you currently have is mostly special.
Running a fully Special set would consume less EV's and focus his Role on the team as a Special Sweeper. However, you seem to like a Mixed Set (based off the set above), so I'll give one that has advantages over both Volcarona and Scizor, who individually would be a better choice.
Genesect @ Dowse Drive
EV's: 252 Atk / 236 Spd / 22 SAtk
- Iron Head
- Techno Blast (Water)
- Thunder Wave
ParaFlinch set that has the ability to Pivot on a switching foe that plans to shift with a Pokemon that has Heal Bell. U-turn is for both STAB and what was said before, and Iron Head also serves as a STAB attack but works well with Paralysis. Techno Blast is used because you seem to want to cover its 4* Fire weakness, and while I'd rather sace the Item slot and go for Hidden Power Water, your Genesect seems to be an in-game Pokemon, so this isn't possible by easy means (unless you hack). Thunder Wave is what officially sets it apart from Sicor; Paralyze the opponent to open up KOes for your skower Pokemon, or simply Iron Head them to death and watch as they either Flinch or be Paralyzed.