Trouble is that Mankey SV can OHKO Luxray. The same goes for Relicanth SV as well since most likely, your going to have a Pokemon Tool attached to Luxray.
The Pokemon Power Bright Look doesn't sound like much, but it really has many more benifits than you realize. You can lure out the Baltoy's or Claydols and try to KO them with your Luxray GL. After that, your opponent won't be able to recover after the heavy loss of the Baltoy/Claydol knockout from Luxray. Also, it can be a great late game sweeper, whenever your opponent has 50 or 60 HP Pokemon on their bench. Bright Look it and knock it out with Flash Impact or Trash Bolt.
It goes with Blaziken or Infernape, due to the mere fact that it covers the weakness to water Pokes. Also, if you wanted to power up Rhyperoir SV (the on that does rage), you can keep on putting 3 damage counters on Rhyperior SV from using Flash Impact. Eventually, Rhyperior will have so much damage counters on him from the constant Flash Impacts that he will beging to knock out one pokemon after another.