Its old and got some horrible advice in it, if you REALLY want me to, I'll go through it and pick out all the valid advice and tips and post them on here for you.
and deadlord santa, I've worked VERY hard on keeping this boards clean and giving straight advice, the fact you mentioned yourself and emblem when I've been doing quite alot and rarely seen you around, is abit questioning. Don't toot your own horn unless you have a reason to. But if you do, you better mention me as one those wise marth board members!
You're right about some of the advice being..meh..so Ill go through it and get the "somewhat" usable advice..now it'd be much better for someone else to write this, as these were wrote a long time again and probably arent too good.
Anyway, looking through the old crappy guide now. (For spacies, I'm not going indepth on chaingrabbing as people mostly know it)
Falco: his main approach involves short hopping his lasers as he gets closer, take to the air and space your jumps well to reach him if its a larger stage or put up your shield and wavedash closer quickly till you can reach him with a good jump. Thats the safe way, if you know your stun times and spacing, you can eat a few lasers and swipe him in return after your stun.
If the stage has platforms, waveland off of them to get faster but do not remain on them unless you want to take a ton of damage. Falling with a counter is a very good surprise tactic as theres not much you can do safely with a falco under you with platforms. His main form of damage will be shine combing you, at lower damages, you are going to just have to di and pray. But after 50%, you can tech out and regain yourself. Of course chaingrabbing comes into play but the use of the counter can either be redeeming or kill you faster.
Try to chaingrab on the flatter stages and if the stage has platforms, be gay with uptilts and f-smashes. Learn his recovery and learn to abuse its horrible vertical height.
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http://www.youtube.com/watch?v=nw8S35JN6Uc watch till end for counter use, very surpising)
Fox: Hes faster than falco but his ground attacks are weaker and his laser has no stun. Be careful of the laser damage, it can put you into the damage range for death without you knowing. Around 90%, an up-smash will kill you and so will an up-throw to u-air. Try to smash Di out of the U-airs when he catches you in them. Be wary of platforms in this match as he can use them to chain up his u-airs and even go out of screen and give you a u-air that kills you at stupidly low damage.
Despite how badly you want to shart shieldgrabbing, most experienced fox players want you to start doing this so they can combo you more. If you do get a grab, chaingrab them to your best ability.
Captain Falcon: Hes fast, hes mean, hes going to knee you in the face over and over till you die. Falcon can chain up Nairs or Uairs on you like mad so try to stop the combo soon as it starts to prevent an early death. His main approach will either be a nair or a dair, the dair props you up, perfect for his knee to connect to your skull. Your air attacks will out-proporitize his if you can make contact. Also, a really great way to stop his combos from ever starting is to up-tilt, it stops his assault from the air completely and sets him up perfect from combos. Watch out when you tech out of his combos, he might can still reach you with his over-b and continue the combo. Be very wary of platforms, if he gets below you, panic and get off that platform..he will begin to u-air you till you die. His recovery is horrible thank god, you can gimp it all to pieces. Most falcons will sweetspot so be ready to switch down to edgehog at the last second, make them think you are going to try and hit them then suddenly grab the edge. Most good falcon players will ledgetech consistently so if they do come up high enough, follow up whatever you hit them with, that sole f-smash isn't going to kill them, you keep them coming. Amazingly enough, if you leap out and n-air him as he returns only using your first jump, it usually does the job if you learn to connect with the second hit and have the lag gone by the time you desend from the first jump so you can return to the stage. He can space very well with his dash dancing and cause ou to whiff then punish, be careful.
Sheik: Marth's supposed counter. She is all too fast and her combos are cruel so a marth really has to watch himself. Do not become predictable at all..Sheik loves to shieldgrab you and punish you for it. Be wary of her grabs, shes going to combo you all day from them. Up-throw to up-tilt combos do very well as you can force her to use her second jump, then combo right into f-airs and send her off the edge. Keep your jumps low to the ground and do not use your double jump without a very solid reason. Edgehog against her for the most part as you can force her to land onstage, at least getting you another hit if you can't get the kill. Her fair is powerful and fast, and can stop you if you try to interrupt her returning to stage but with correct di, you can live at very high damages..although her u-air negates much chance you have of living very long as it will kill you around 95%.
Samus: She loves ccing and counter attacking. Space yourself perfect in your fairs if you do not want to learn how well she can hit you back. A shuffled dair will put a stop to her ccing ability and give you the upper hand in comboing but don't become predictable. Her missile spam can get very annoying, and if you take to the air and swipe them down, can put you in a vunerable position. Depending on the stage, your methods of reaching her will vary. On long flat stages like final destination, I take my time approaching using simple neutral a's till I get a distance where shes going to be vunerable if she fires another missile, as you can swipe both her and the missile at the same time. On stages like stadium, its harder since she has platforms to chance. On stages like battlefield, she can missile cancel extensively but you should be expecting this and be able to manuver around it. The first hit of your nair will swipe a missile down and the second can be used to attack, just to mention. Watch her d-smash as most samuses love to combo with it, di that up at higher damages so you aren't sent off the edge far at all.
She has many methods of recovery and can mix it up well. She will normally bombjump back to stage, going out and back-airing her works will but be wary of the fact she can attack as she is coming back. Try to knock her out of her stance when she uses her grapple so she is forced to use her up-b and then you can edgehog, a samus without her grapple is much easier to predict. If she is foolish enough to come in with alot of height, leap up and dair..but do so enough that if she airdodges, she won't be able to make it back on stage and she'll either have to press her luck by attacking or trying to manuver away, either way, its better for you.
Peach: Despite what you hear about marth being a peach counter, she can give you a very hard time. Do not shield her d-smash as it will most of the time get you hit, lightshielding her d-smash on the other hand works well. Dashing away after your aerials is a must, moreso than in other matches. Your spacing really needs to be at the top of its game as the d-smash and her dash attack have the amazing ability to catch you despite you moving away from her quite fast. Her dash attack will cut through your aerial attacks so don't underestimate it. She can also up-smash out of shield so its like shes utterly anti-air. She can live to obscene damages so its best to go for the kill early. She also has a great f-throw, launching you very hard and fast..di-ing this up is a life saver and can make your marth live much longer. Not all is lost though, you can f-throw chaingrab her for abit from 0% and get in a few easy f-airs. Your combos on peach come easy but its best to end them early as well. Peach's nair is the ultimate combo breaking and you need to know this well. Edgeguarding peach can either be easy, or impossible, depending on her height. Doing a rising d-air against peach when shes coming back(floating) works very well if you know how to be unpredictable with it.
Her turnip game can be very threatening if she knows how to use them, do not catch the turnips as it limits your game dramaticly. Swiping is only a good idea if you think shes going to approach you and you aren't moving further, as the turnip keeps its hitbox. Stitchface is extremely deadly and trying to catch him in a pressureful match is not advised, just avoid it at all costs. Shes going to be throwing these at you as you try and make it back, then is a good time to wack them..but as a rule of thumb, always save your second jump if possible as you're going to be coming in very low..
She also as the d-smash to edgeguard you, which will kill you in one fell swoop if you do not tech it, if you tech it, you get another chance at life...I've ledgeteched and immediately u-air-ed before..sometimes it hits, sometimes it doesn't but one thing is for sure, do not wall jump tech.
If you must have the others done, I'll get myself and a few others to write up better mini guides and post them.