Let's say I have a $30 MM character locked Mario vs. Luigi MM this weekend (I'm using Mario, my opponent is using Luigi)
What stages should I strike to?
What should I be looking for MUwise (details help)?
What stage should I ban?
What stage should I CP?
When am I in kill percent against Luigi?
Any info would help
It's already been said, but for further emphasis' sake, don't go aggressive AT ALL against Luigi. Trades WILL happen since you both have a lot of the same frame data same general range, but stuff like Luigi's nair and bair will not trade in your favor because he kills earlier than Mario and his attacks put you into better positions for follow-ups. Instead, play a heavy zoning game. Fireballs, bair, jab, utilt, ftilt, and the occasional Fsmash will work wonders. Abuse your OOS options where applicable...just be careful with upB for obvious reasons. Pursue damage only when he's offstage or on a read. Other than that, just zone the **** out of him.
Usmash is GREAT in this match-up for punishing landings since it will cleanly beat all of his aerials and he can't maneuver all that well through the air. Charge it for airdodges, let it fly if he tries to power through the nair or dair or something.
Don't underestimate the strength of caping his fireballs. They help him close in space, and caping denies that every time.
Jab cancels are still useful, just be wary that Luigi's are better, lol. It's technically the same move that positions better. Same speed, same dmg IIRC.
Our Fsmash is really good here because Luigi's traction makes it really safe on shield. It also beats all of his attacks as far as range and priority go because of the disjoint. At mid-range, it's incredible. Just don't whiff it, lol.
I haven't really tried this much, but Uthrow may be a better choice for damage than Dthrow at low percentages vs Luigi. It does more base dmg (9%) and though it positions him hier up than dthrow, you won't have to worry about him nairing through follow-ups. His airspeed won't really allow him to avoid punishment on his landing, and Usmash/Utilt will be good from below too. Give it a try on your own and see how you like it.
Luigi is good where we are, generally. Your best bet will just be to go wherever you're comfortable. FD MIGHT work since you don't want him closing space easily, but regardless of where you go, he'll combo and kill leagues better than you. Just remember that you can abuse his weaker approach options and lack of a great defense well. FLUDD is also stops green missle completely, if you weren't aware. It may help you when he's recovering.
His Fsmash will kill around 90% with DI and upB around 50 or 60%. His nair kills around 125% with DI but that depends on your positioning. Bthrow kills around 150% I think. Usmash is weird...sometimes I've seen it kill later than Mario's (around 140%) and sometimes I've seen it kill way lower (110%). Just assume it's the latter and you'll be fine.
Best of luck