Luxio is the evolved form of Shinx and the pre-evolution of Luxray in Pokemon Brilliant Diamond and Shining Pearl.
Known as the Spark Pokemon, Luxio is one of the few Electric-types that can be found in the initial Sinnoh Dex of Brilliant Diamond and Shining Pearl. That makes it a common choice for players to use on their journey.
Trainers can opt to grow it for a while without evolving it into Luxray as soon as the requirements are met. Luxio evolves into Luxray at level 30 in Pokemon Brilliant Diamond and Shining Pearl.
There are a couple of ways to level up Luxio in Pokemon Brilliant Diamond and Shining Pearl. They are both pretty straightforward and will lead their evolution into Linux.
The first method is by simply leveling it up from battling. EXP is gained after each successful Pokemon battle, whether a wild creature is caught, fainted, or a trainer is beaten.
EXP Share used to be an item to give to a Pokemon, but it is now a normal part of the franchise. If Luxio takes part in the battle, it will gain more EXP when an opponent faints.
Otherwise, it will gain a small amount of EXP just for being in the battle party whenever the battle is complete. After a certain amount of EXP is acquired, the Pokemon will level up.
Once Luxio hits level 30, the evolution cutscene will occur and you will see Luxio turn into Luxray. Of course, you can press B to cancel the evolution process and wait for it to level up again.
At that point, every time it levels up, you'll be shown the evolution. Catching Luxio in the Grand Underground at a higher level or having a plethora of Rare Candy in your bag are other methods of reaching the evolution stage.
A Rare Candy will raise a Pokemon by a single level each time. You can do that until Luxio reaches level 30 or raise it by a level after 30 to trigger its evolution.