While this question has been answered, I'd like to go more in detail.
-Base Speed of 130, so it will end up outspeeding quite a bit.
-Its base Special Attack and Special Defense are also great, at 110 and 95, respectively.
-Learns Shadow Ball for Allister, Thunderbolt for Nessa and Leon's Charizard, Double Kick for Piers (though its attack isn't very good), Iron Tail for Melony/Gordie (again, bad attack stat), and Dig for Raihan's Duraludon and Leon/Hop's Cinderace (unless you chose Cinderace) (though, again, its attack isn't very good), to name a few of it's coverage options against major battles.
-Some of its coverage options are physical, and it has a terrible base 65 Attack.
-It has a shallow Special moveset as well, really only having Discharge, Thunderbolt, Hyper Voice, Shadow Ball, Volt Switch, and Stored Power (with a boosting move such as Work Up or Agility) as decent Special moves.
-Its Defense is base 60 and its HP is base 65, both of which are pretty terrible.
-Has great base 120 Attack and decent base 95 Special Attack, so it makes a good mixed attacker.
-It gets Bite/Crunch/Throat Chop for Allister, Thunderbolt and Wild Charge for Nessa and Leon's Charizard, Play Rough for Marnie and Piers, Superpower for Marnie and Piers, and Iron Tail for Melony/Gordie.
-Its Speed isn't very good, but it gets Agility to boost it, so it shouldn't matter too much.
-It has a great movepool, both physical and special.
-You probably won't be using Guts in game, but Intimidate is a great ability, boosting its physical bulk.
-Hits harder physically than Jolteon does specially.
-I'll also list its poor Speed as a con. With all the coverage it gets, I feel like its hard to fit Agility onto a moveset.
-In the event that you do use Agility on it, set up is very unreliable in game (in my opinion, at least).
With all of that said, I would use Luxray over Jolteon.
Hope this helps! :)