Double dance rock gem Terrakion is IMO best set, as LO is not needed for power and it helps storm past usual counters.
One set that can do well in any tier is the standard Acroblimp, which I have used to some success even in OU. It's a bit like an offensive sableye. Drifblim is also the only poke where a gem has 3 uses: Acrobatics, powering up STAB and unburden.
Drifblim @ Flying Gem
EVs: 252 Atk / 200 Spe / 52 HP
Adamant Nature (+Atk, -sAtk)
-Substitute / Shadow Ball
Another niche it has is it can have the speed of Venusaur in the sun, so more speed can be added if your wish is to outspeed and kill Venusaur.
Breaking in my new account after lurking for months. Use Honchkrow more, 'nuff said.