Couple things after a quick glance.
Also, dair is cool, but borderline situational and not going to be used too often unless you are using poor, predictable recovery habits.
Edit: Fair autocancels iirc, just as long as you aren't on the very end of the animation, and even then, the lag is very minimal.
All true. Fair does cancel and can easily lead into more traps and tech chases. And unless your recovery is extremely predictable, you probably won't be seeing dair much. If you recover low, Marth can go for the stage spike.
If you don't sweetspot the edge prepare to get uber punished.
play defensive unless your able to get inside marth(by inside i mean being able to jab him)
Don't rely on this; it won't happen often against a good Marth. Even then, what are you going to do? Jab? Marth can easily fair your tech chase and reset the situation to neutral. That is if he doesn't call your jab cancel and you eat a dolphin slash to the face. Ftilt is too slow when you're this close and utilt might work...for a bit.
dair'ing early and using the lag of his retaliation to dair him again, but hit this time.
It's really not hard to see this coming, seeing as how every Lucario does it and his dair is well known to be his best move. Reverse the lag situation, only it's better for Marth since his uair has more range (iirc). Marth is one of the best jugglers in the game, even against Lucario's awesome dair. Dair spam won't work, play smart. Also remember Marth doesn't have to juggle with uair, utilt outranges dair too.
an offstage marth is a marth that's in trouble against us
If you're smart.
we can chain 2 or 3 FPs before he can upb our face, what i like to do is just shield after the 2nd FP and see what he does, which is almost always upb in my experience.... now look how vulnerable he is!
Not sure about this. Has it been tested? Good Marths play smart and know how to read opponents. If it's obvious a DS is coming and you shield, you might get grabbed. Otherwise, I'm pretty sure Marth can DS right out of the chaingrab immediately. This only works at lower percents too since you can DI out of it at higher ones iirc.
Do you feel Lucario has an advantage in any particular scenario of this matchup?
KO power, marth will have trouble killing us if he does not land down a tipped fsmash
Marth's smashes are punishers, not killers. You can quickly get to higher percents without even noticing it with DB chains and before you know it, tipped fair KO. Or utilt. Or uair. Or nair. Or bair.
his upB cant really KO up till a fair bit after 100%
See above.
usmash beats him from below, but it shouldnt be used much(be sure you will hit).
Marth is TERRIBLE when his opponent is beneath him. But usmash can be predictable and most people don't aim to land directly on top of you...Also, DB can stall in the air. Lingering hitboxes can be problematic though.
Do you feel the opponent can shut down aspects of Lucario's game?
somewhat, AS appears to be a pain in the arse for marth
Eh. Jab + PS = not a big problem.
we cant really shut down his air game due to inferior range
Yeah.
Counterpicks? What to avoid and what to enforce?
stay away from battle field at all costs, its called marthland for a reason.
I love Battlefield =D
It's a pretty big deal for Marth I think, considering if he's just throwing you, you take 4%, and at higher percents that grab doesn't set up into anything.
Marths grabs aren't used for damage, they're used for setups. You might not worry about the 4%, but then you take another ~17% from DB. At higher percents, grabs can be used for pummels to refresh his moves and Marth will put you where he wants to.
Grab --> pummel --> throw off stage --> fresh tipped fair.
Also, him being above you = **** time. Marth has relatively few options that are effective below him, since fair has bad vertical range, dair/AD is very punishable in juggling, and counter just doesn't hit below him much. So if you get him above you, uair or bait a dair/AD, then attack with either uair or double jump -> dair.
Baiting the AD is probably the best option.
Oh and if you mean dsmash Timbers, that comes out on frame 6, and btw, dsmash is something that imo is overlooked as marth, it's his quickest smash, and it tips pretty easily. Can kill pretty well too, so don't count it out of the discussion
It works wonders OoS, which is usually how it's used.
That's all for now. I honestly haven't read everything carefully, so I'll look it over some more later.