Luigi has Campy/Smart/and STUPID.
Stupid consists of Aggro/etc.
Smart can't be a playstyle. By categorizing smart as an individual playstyle, you're implying that the others don't require being smart or thinking, and are just mindless playstyles. Smart is just what is needed to make a certain style effective. Again, your definition of Smart was right, but putting it as a playstyle doesn't work. It's general knowledge of how to play the game, not how to play the character.
If you play a campy, defensive Luigi, then to play smart, you need to analyze and punish the enemy approaches perfectly, and keep a solid distance between you and the opponent.
If you play an aggressive Luigi, then to play smart, you need to pressure the defense and look for the slightest hole in the wall to abuse and pound through. You need to counter any defensive maneuvers as you mow them down.
Also, Aggressive= Stupid? So you're saying Boss, the Luigi who EVERYONE knows is the best, and has a huge gap between himself and the rest of the Luigi players, is stupid? That's not how it works.
ALias pretty much got it right on the dot with the basics of Luigi playstyles. Smart isn't so much a playstyle in itself, but the key to make a playstyle succeed.
TL;DR version: Defense, passive-aggro and all-out aggro are the 3 basic styles. Smart is just the oil that keeps those machines running.