Wow, no ones posted yet? Let me try my hand...
Brave Nature 252 HP/252 Attack/4 SpD
Super Power/Crunch/Stealth Rock
This is a set I intend to utilize with Trick Room support, which is why he has the Brave nature to enhance his speed under the Trick Room setting. Outrage shouldn't need much explanation but Dragon Claw is slashed if getting locked in becomes problematic. We all know from TLC that Stoutland can 2hko Escavalier with Fire Fang so using a Sheer Force Boosted Fire Punch should be able to put a dent into the bug, as well as providing unresisted coverage. From there I went with Thunder Punch for super effective coverage on any bulky waters, primarily worried about Slowking as he can take some hits. Super Power if team needs the fighting type coverage, Crunch if we're going to need help with Ghosts/Psychics or Rocks if nothing else can carry it.
Anyway, Druddigon has many utilities outside of this set, as this is pretty much just a sledge hammer (ease of use but may be clumsy in application). He's most famous for running a Rough Skin set that ParaShuffles with Glare and either Roar or Dragon Tail, if not both. He can use a beastly CB set focusing on 'Dragon/Outrage Spam,' as well as sets focused on setting up Rocks or other offensive/support options.
Druddigon is also one of the few pokemon that I can think of that can utilize three very good abilities and can tailor sets to each. There are many ways to utilize Mold Breaker, from using Earthquake to hit levitators to ensuring Roar doesn't get foiled by a pokemon ability (only one I can think of is Sound Proof but...). Sheer Force used to be his least useful ability but got a boon in the new Move Tutors, Thunder Punch and Fire Punch being two nice additions to abuse in addition to Crunch and his old stand bys. Rough Skin has been his favored one from what I can tell: he's bulky and can take a nice chunk out of a phsyical attacker just by taking hits.
Anyway just wanted to get some dialogue going about my favorite dragon :)
Here's a set I saw Dragon Rider post with a small twist from myself.
Mold Breaker/Rough Skin
Careful/Sassy Nature (252 HP/252 SpDef/4 Def)
Forget where this was posted and have since seen a similar set to this utilized by Giratina in Ubers. The main purpose of this set is to phase reliably and works best with hazard support. The original set as posted had Rough Skin and a Rocky Helmet, which may be a better set up, but I'm going with a set up that ensures that he can phase no matter the ability of the pokemon on the other side. I'm guessing this is beyond niche so the Rough Skin set up may work better in application but the Mold Breaker twist has stayed with me since I saw the post.