This is Bagon's only viable set in LC, and just like its evolved form Salamence in OU, this set is used to not only heal itself and its team with Wish, but to tank attacks as well. While it doesn't have the biggest HP stat to pass Wishes with, its typing gives it useful resistances to common offensive types such as Fire, Water, Grass, and Electric, which gives it its niche. Dragon Claw is used for damage purposes, as well as to prevent Bagon from becoming Taunt bait. Fire Blast hits Steels, mainly Magnemite and Ferroseed, that will try to use Bagon as setup bait. Protect is used to ensure Bagon gets the recovery from Wish, and it also works with Toxic Spikes as it stalls out poison as well. However, if you aren't concerned about getting guaranteed recovery from Wish, Toxic can be used over Protect, as it breaks down Pokemon such as Mienfoo, Hippopotas, and others.
With maximum HP investment plus the maximum investment Bagon can have with a Relaxed nature, Bagon has as much physical bulk as possible. Bagon can 2HKO Magnemite and it even has the chance to OHKO Ferroseed with 36 Special Attack EVs. After the aforementioned 36 SpA EVs are used to deal with Magnemite and Ferroseed, the remaining EVs go into SpD, as that is the only place where those EVs have any use. Using an Eviolite on this defensive set makes sense, as it boosts both Bagon's Defense and Special Defense.
Roar can be used in the last slot as it works like Dragon Tail: phazes out Pokemon and racks up entry hazard damage. Other attacks such as Zen Headbutt, Crunch, Rock Slide, and Brick Break can be used over Fire Blast for a Wish passer that can deal with certain threats. Zen Headbutt can deal with Mienfoo and Croagunk, Crunch with Misdreavus and other Ghost- and Psychic-types, Rock Slide handles Larvesta, and Brick Break hits Pawniard and Ferroseed. If you decide to use one of those attacks over Fire Blast, make sure to move those Special Attack EVs into Attack.
Teammates for Bagon should do two things: provide entry hazards to spread damage or status, and enjoy the Wish support Bagon can provide. Pokemon such as Omanyte, Dwebble, Ferroseed, and Pineco all love Bagon, as they can set up Spikes, and Pineco can even Rapid Spin, which is extra helpful. Dewbble, Omanyte, Pineco, and Lileep can all set up Stealth Rock as well, while Omanyte, Trubbish, and Tentacool all set up Toxic Spikes. Pokemon that can keep those hazards on the field are useful partners as well. Misdreavus is a great example, as it can block Rapid Spin, and loves the Wishes. Magnemite is another great teammate, as it traps Steel-types if Bagon isn't running Fire Blast.
While you might still have doubts about Bagon's ability to tank common physical attacks in the LC metagame, below are calculations that show just how sturdy Bagon is:
236 Atk+ Drilbur Earthquake vs. 236/196+ Bagon 54.54 - 68.18%
236 Atk+ Mienfoo High Jump Kick vs. 236/196+ Bagon 54.54 - 68.18%
156 Atk Mienfoo High Jump Kick vs. 236/196+ Bagon 45.45 - 59.09%
20 Atk Hippopotas Earthquake vs. 236/196+ Bagon 31.81 - 40.9%
212 Atk+Tirtouga Stone Edge vs. 236/196+ Bagon 40.9 - 54.54%