I definitely recommend Choice Scarf. Though it has some minor issues with tackling some threats like Mega Metagross and plagued by a weakness to Bullet Punch and Water Shuriken it is one of the better answers in the tier to a lot of top tier threats and can snowball off of them thanks to Beast Boost. I really wish the OP would list it as the first set.
Much like bludz stated your best moveset is as follows:
- Power Gem
- Sludge Wave
- Thunderbolt
- Hidden Power Fire / Hidden Power Ice
- Fire to catch Scizor / Ferrothorn. Also can take down a weakened Mega Metagross possibly.
- Ice catches Landorus-T, Garchomp, and Zygarde provided the Zygarde isn't behind a Sub and is missing some health.