Well, my main against my secondary.
If u posted this on these boards, that probably means that u search for advice on how to play Luigi. Now I can tell you that, but I'm sure you already got it from the other members, besides, Luigi is a simplce character so reading the guide once or twice BUT A LOT of training and matches and U'll do just fine.
FOr Lucas help you should post in the Lucas boards but since my secondary is Lucas i'll just give you some tips n tricks.
Lucas is a very complicated characters, maybe the one with most if not the one with most(besides Link and Yoshi and some other chars) AT's. A lucas palyer also uses a lot of mindgames, especialy PK Thunder. Watch out for B-sticking if ur friend is rly into Lucas and changed his C-stick to B. B sticking is some srs mindgaemz(XD), but srsly, It's not something to mess with lol. Also watch out for SH>Dair, It's a move almost impossible to dodge and a ever worse it can be repeated many times, so spot dodge if he short hops close to you. Lucas's Bair can spike. Yes, spike if u didn't know that untill now. I think Dair can spike to but Bair is Lucas's spking tool. Nex thing is D-tilt. If Lucas gets close to, like really close(you know that moment when u just feel right to FIRE PUNCH ur opponet with Luigi? Like, the moment when u and ur opponet are standing in practicly fuzed? Well, that close), watch outfor that coz that thing can rack up many many hits, I think it's one of best Dtilts in teh game. PK freeze. Yes, PK freeze. A pro Lucas players don't use PK freeze untill your opponet is off guard, that one time, when u r at least expecting a PK freeze, Pro will use it and freeze u so he can pull of Usmash. Oh and last but not least, Lucas's Usmash. Lucas has second most powerful Usmash in the game(except Ivysaur), but I think it has most hitbox. It is VERY powerfull so never get right above Lucas. It also needs some time to pull off so it's kinda a slow move. Well that is only fair, considering the power and space it has.
I hope that helped, now these r just things about how Lucas does in a battle. I can't really give u any tips and tricks on hiow to fight a Lucas sorry, well, except this one(gimping).
To easily gimp lucas all u have to do is cancel his Up b, now, pro lucas players usualy recover right above the stage to sweetspot the edge. Now in that case don't be near the edge cuz they can change their mind and knock right into you. Also I suggest not trying ti gimp Lucas while he's performing a PK thunder UNDER the stage, small chance u'll do it besides ull get gimped easily. ALSO, one last tip. DO NOT, I repeat DO not be that stupid to ledge grab when lucas tries to recover, NEVER. Not only the PK thunder will get u out of edge, you will most likely get gimped.
There, I hope that helped, that was a lot to type XD