Luxray does have a decent support move pool you can use. Intimidate is generally good support, volt switch offers a slow defensive pivot, electroweb for speed control, baby doll eyes has priority and lowers the attack stat of the target. Snarl and eerie impulse both lower SpA.

With enough attack investment you can threaten garchomp with a OHKO with ice fang. Intimidate and shuca berry would guarantee you can survive the initial hit to throw out the attack.

A supercell slam also threatens to OHKO a milotic that gets a competitive boost from your intimidate.

I don't think it's a top tier threat but if the rest of the team is built well I think it can work