I think this is the best potential Luxray set
Luxray @ Choice Scarf
Ability: Intimidate
EVs: 252 Atk / 4 SAtk / 252 Spd
Adamant / Jolly Nature
- Wild Charge
- Crunch
- Superpower / Ice Fang
- Volt Switch
With an Adamant nature, Luxray outspeeds everything up to (and including) max Speed base 112s (up to and including base 128s with a Jolly nature). Wild Charge is your obvious main STAB. STAB on Crunch has some nice perks, like being able to guarantee an OHKO on Gengar. Superpower hits Steels harder than your STAB options, and is also a clean OHKO on Bisharp, who could cause problems after getting an Attack boost with Defiant. Ice Fang can hit Dragon, Gliscor, and Landorus that otherwise cause problems. What's really fun is Volt Switch; while it doesn't do much damage, it's great for scouting (You could opt to run a Naughty or Lonely nature or even some SAtk EVs to power it up).
What I find notable about Luxray in general is that it counters Talonflame completely. It takes around half damage from Adamant Banded Brave Bird. The only thing it has to fear it Flare Blitz, and even that's only a 69% chance to OHKO (and Scarfed Luxray outspeeds Talonflame anyway). It can also have some fun with Aegislash, doing around 65% to max HP shield forme, and a clean OHKO on blade. It doesn't fear being revenge killed by Shadow Sneak thanks to its new typing, although Sacred Sword usually OHKOs, and it has to watch out for King's Shield.
An Assault Vest set could also be fun, or even a physically defensive one with something like Roar, Thunder Wave, Crunch, and Volt Switch.
Here's some calculations (I did take the new STAB on Crunch into account):
Offensive:
252+ Atk Luxray Crunch vs. 252 HP / 0 Def Aegislash-Shield: 192-228 (59.2 - 70.3%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Luxray Wild Charge vs. 4 HP / 0 Def Talonflame: 404-476 (135.5 - 159.7%) -- guaranteed OHKO
252+ Atk Luxray Wild Charge vs. 252 HP / 252+ Def Mandibuzz: 212-252 (50 - 59.4%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
252+ Atk Luxray Crunch vs. 252 HP / 4 Def Deoxys-D: 182-216 (59.8 - 71%) -- guaranteed 2HKO after Stealth Rock
Defensive (the +1 Atk is for Pokemon that used Swords Dance and took an Intimidate, or Defiant in Bisharp's case):
252+ Atk Choice Band Talonflame Brave Bird vs. 0 HP / 0 Def Luxray: 143-168 (47.5 - 55.8%) -- 81.6% chance to 2HKO
+1 252+ Atk Aegislash-Blade Shadow Sneak vs. 0 HP / 0 Def Luxray: 72-86 (23.9 - 28.5%) -- 97.3% chance to 4HKO
+1 252+ Atk Life Orb Bisharp Sucker Punch vs. 0 HP / 0 Def Luxray: 165-195 (54.8 - 64.7%) -- guaranteed 2HKO
+1 252 Atk Mega Absol Sucker Punch vs. 0 HP / 0 Def Luxray: 132-156 (43.8 - 51.8%) -- 14.1% chance to 2HKO
+1 252 Atk Aerilate Mega Pinsir Quick Attack vs. 0 HP / 0 Def Luxray: 89-105 (29.5 - 34.8%) -- 9.8% chance to 3HKO