Druddigon @ Life Orb
Trait: Sheer Force
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature (+Atk, -SpA)
- Fire Punch
- Sucker Punch
This is a good offensive set, which capitalizes upon all the positive aspects of Druddigon, and tries to make up for its disadvantages. Outrage is the best STAB option and the lack of general Steel-types means that nothing will be able to take it. Sheer Force is the primary ability as it powers Druddigon's punches and still has LO boost but not the recoil! Fire Punch takes down the Steel-types that resist Outrage, also Fire Punch is to hit Grass-types without locking into Outrage. Sucker Punch is the cherry on the top, as then it can take on weather, sweepers, or anything faster than itself. ThunderPunch is most a utility attack that isn't going to be used as much as the other ones. It's useful to hit Moltres' that think that they can set up a Substitute on Druddigon while it uses Sucker Punch. Additionally, it hits general Water-types for excellent damage.
What sets are popular and effective?
The most popular set is one that 'mike posted above, which utilizes Druddigon's bulk as well as Glare and phazing to infuriate the opponent. The reason why the support set is so effective is because of its bulk, Rough Skin, and unique traits that not many other Pokemon have. Also, access to Stealth Rock just makes everything better, so it can support the team!
What general roles and niches does this Pokemon fulfill?
A general niche is one of a supporter, as a sweeper set is too slow outside of Trick Room, and Trick Room isn't a popular archetype, so it doesn't much use. The mono Dragon typing is useful as then it has key resistances to Water-, Fire-, and Grass-type attacks. Rough Skin makes Druddigon an excellent check to physical attackers, and when combined with Sucker Punch makes it a decent check to fast sweepers.
What advantages does it have over the other Pokemon with these roles?
The biggest advantage is definitely its typing and bulk. Dragon typing makes it an excellent switch-in to Water-, Fire-, and Grass-type attacks. Rough Skin makes sure that physical attackers are punished even further. Sheer Force powers up Druddigon's other attacks that are used less, such as the punches. Glare allows it to paralyze Ground-types, notably Nidoqueen, although the accuracy is a bummer.
The Speed is definitely the ultimate downside, combined with a lack of any setup attacks such as Dragon Dance, or Swords Dance, although it does have Hone Claws but that doesn't help the Speed.
Druddigon is an excellent check to fast and frail sweepers thanks to its excellent bulk and Sucker Punch, but this does mean that it can be outpredicted and be setup on. Also Pokemon such as Tangrowth and Slowking are excellent Pokemon to switch into, as their attacks are easily shrugged off (Tangrowth's case only if Sleep Powder is used). Druddigon threatens almost eveything, especially anything slower. The safest switch-ins are Steel-types but even then a Fire Punch will put a dent in them, otherwise nothing will want to take an Outrage. The technical definition of counter doesn't exist in RU, so there are some checks available. A boosted Outrage will 1-2KO everything, and Steel-types will not want to take a Fire Punch.
Druddigon hates status especially a burn, as then its power is crippled; poison also gets rid of its bulk. To help this a Cleric would be best, so Clefable or Lanturn is great to have. Clefable will be able to wish pass, whereas Lanturn is a slow Volt switcher so Druddigon can switch in safely.