Few things off the top of my head:
1. the Nair for Luigi in Brawl got buffed ALOT. Coupled with high priority thats the move i use to ko people are higher percents when they are in the air.
2. The firepunch seems to be stronger on the ground then in the air from the little testing i have done with it. In brawl it is a lot easier to use the firepunch: out of a dtilt, out of a twojab combo, or even using Luigi's extended slide physics he has when he runs (slide into the punch).
3. Canceling Luigi's dash with the shield is very important as it can lead into many different moves (like dtilt, tornado, fsmash, utilt etc.) If you don't already know, just tapping the shield halts luigi's dash and negates almost any slide (which as a luigi player you will come to understand just how much the man in green slides).
That's all i can say right now, if i think of anything else i'll edit this post.
