Maxed Speed and HP, Leftovers / Focus Sash;
Sheer Cold (only OHKO which can beat anything)
Lock On / Mind Reader
Recover / Softboiled / Milk Drink / Heal Order
Mean Look / Spider Web / Block
What if you encounter a higher level pokemon and pokemon of the same level? It is a good set, but not to be used for everything....
OHKO moves are not allowed in almost all tournaments, so no, this would not be very useful. Use for Smeargle a Baton Passing strategy.