Here are my suggestions.
1.) Like I always say to every Luigi, work on wavedashing. Get perfect at it. I still practice wavedashing off platforms every once in awhile.
2.) Be aware of wavelanding. IMO wavelanding is more useful then wavedashing. It allows you to follow up your attacks as well and slide you to safety. I generally do sh aerial to waveland rather than 2 aerials.
3.) Jump cancel your grabs. Dash grabs are just asking you to get hit.
4.) Dtilt is mostly useless.
5.) Don't mash B if you are trying to down b offensively. You want to use that horizontal movement rather than the vertical. You can usually get away from a shielding or cc-ing opponent if you just slide by them.
6.) Recovery. Use your air dodge if you want to just get on the stage and not use the ledge. Do not forward B onto the stage if you can air dodge. Forward B has a lot of landing lag.
7.) Against Mario, range is your advantage. You started that match by running up and jab comboing. Don't be so aggressive. Range is about safety.
8.) Try to aim your ftilts up or forward. Ftilt downwards has like no knockback.
Good stuff though. I liked the use of the fsmash.