Well, like the comments said, that't not really the best way to use a Smeargle (competitively, at least). But if you really want to do that, then Aeroblast and Sacred Fire are both very good moves (from Lugia and Ho-oh, respectively).
Darkrai has Dark Void, but that is outclassed by Spore, so I wouldn't bother with it.
For the last move, maybe Bolt Strike? But because the rest of the moves are Special, it probably won't have much Attack investment, so you are probably better off with just Thunderbolt. Unless you want the signature move just because you can. Sacred Sword would also be useful.
So final move set:
- Draco Meteor
- Sacred Fire
- Fusion Bolt/Thunderbolt/Sacred Sword/Spore
Well, I hope that helped. But personally I think Smeargle should stick to either setting up hazards or Baton Passing, as that is what he is good at.