Luxray LA is definitely a big improvement over his DP counterpart. 120 HP is slightly below the 130 we've come to expect of Stage 2s, +30 Weakness to Fighting is ok since Fighting isn't big (yet), -20 Resistance to Metal is...better than nothing, and a free Retreat Cost is excellent of course. Rivalry is an interesting Poke-Body, letting Luxray deal an additional 50 damage if your opponent has a Lv X on their side. As a good many decks use Lv X Pokemon these days (AMU, Torterra, Magmotar, Leafeon, etc), this is a very nifty Body to have. Plasma does a simple 40 for 2 Colorless Energy, and lets you attach a Lightning Energy from the discard to Luxray. Shock Bolt does an impressive 100 for 2 Lightning and 1 Colorless, but you have to discard all Lightning Energy attached to Luxray. A good partner for Luxray is Rayquaza, along with some Energy Swtich Trainers.
Modified - 8/10 (Solid deck, does great against Kingdra and any deck with Lv Xs hanging around)
Limited - 8/10 (If you ever get this out, he has some nice damaging attacks plus can recover Lightning Energy onto himself with Plasma)
Unlimited - 1/10 (No use, is ERed and SERed alive)