I'll go ahead and post my thoughts on Link. He was my main in N64 and Melee and is my secondary in Brawl. Hope I can help. I'll hit the whole cast and drop specific reasons where I deem it necesarry.
Bowser- Without a doubt, Advantage.
C.Falcon- Overall I'd say advantage. Link almost always has an edge against those without projectiles- the captain isn't any different.
Charizard- This ones tough... I seem to have trouble with Charizard, but that may just be me. I'd go with Disadvantage to Link.
Donkey Kong: In all three Smash games I've had an easy time beating DK as Link. Keeping it a long distance battle can secure the win, but throw in Link's quicker smashes and you've got a good chance at outmanuvering him up close. Advantage to Link.
Diddy Kong- In my experiences, Diddy can be trouble. I'd say either slight Disadvantage, or almost neutral.
Falco- With a less effective reflector, I'd say Link now is Neutral against Falco.
Fox- Unlike Falco, Fox's reflector is still a hazard. Disadvantage to Link.
G&W- This guy gives me a lot of trouble. He's too quick for some projectiles and his Smashs are deadly. Disadvantage to Link.
Ganon- Link has little trouble with his slow, weak recovery stricken nemesis. Advantage to Link.
Ice climbers- I'd give a slight disadvantage to Link in this one. I find myself having to fight harder than usual with them. Not sure why. I can say their aerial game seems superior to his by a wide margin.
Ike- Ike may be a powerhouse, but he's slow and has no projectiles. His Counter has irregular timing and his swordplay is outclassed by Link's. Link has a clear advantage over this predictable FE character.
Ivysaur- In general combat, I can see Link struggling a bit thanks to Ivy's powerful Smashes. But when it comes to KOing Ivysaur, Link has the Advantage. Ivy's lack of agility in dodging slashes and tether recovery is far too easy for Link to stop. I'd go with Neutral, considering the different strengths.
Jigglypuff- No projectiles, slow and light, and ineffective specials against a long-range fighter. Advantage to Link, no doubt.
King Dedede- Advantage to Link, another case of a slow heavyweight falling prey to Link's fast slashes and projectiles.
Kirby- Like DK, I've easily been beating Kirby with Link for three games straight. Just me? I think not. Advantage to Link.
Lucario- Lucario's got an effective counterattack and multiple recovery options... Combine these with his damage ratio-aura ability and you've got Link at a major disadvantage.
Lucas- Hm. I'd cal Neutral on this. Neither has a clear advantage. Though it could be tipped in Link's favor since Lucas can't heal from Link's projectiles.
Luigi- Same boat as Lucas, really. Luigi and Link are on fairly even footing. Neutral. Too bad Luigi doesn't have Mario's cape.
Mario- Unlike his brother, Mario has the cape. Ruins Link's projectile game... And Mario's recovery is kind of hard to stop thanks to Wall-jumping and his Up-B. Disadvantage to Link.
Marth- Marth has the quickness and effective Counter that Ike lacks, making him much more of a challenge for Link. I'd lean toward Disadvantage to Link, but it could also be Neutral. Marth's reliance on close combat sort of leads me to the Neutral conclusion.
Meta Knight- No projectiles, light, vulnerable to bombs/arrows, easy to combo with Link's sword swipes. I'd give the Advantage to Link.
Ness- Same boat as Lucas. Neutral.
Peach- Peach is highly vulnerable to Link's sword attacks. bombs, and Spin Attack. Advantage to Link.
Pikachu- Unlike Kirby or DK, Pikachu has been giving me trouble for three games. Too quick for a long distance fight and can easily outmanuver poor Link. Disadvantage to Link.
Olimar- Olimar easily outclasses Link in Smashes and damage building- two key areas for defeating Hyrule's hero. Were it not for his weak recovery, Olimar would have a huge advantage. I'd still give Link the Disadvantge here, but not by much.
Pit- Pit can reflect projectiles with two moves, can also be a long distance fighter, has quick smashes, and one of the best recoveries in the game. Disadvantage to Link.
R.O.B- I want to say Neutral, but I never struggle with ROB. It seems like I can pretty easily break any camping or 'specials' reliance on his part. Advantage to Link.
Samus- With her Charge Shot lacking in power this time around and considering her bombs aren't nearly as useful as they once were, I'm giving it to Link. His projectiles simply outclass hers and she isn't swift enough to dodge them. Not to mention he's superior in the air and in recovery. Advantage to Link.
Sheik- I'd go with Neutral here. I see no clear advantage to either side.
Snake- Outclassed in the air and on land, Snake is an easy target for Link. Advantage to Link.
Sonic- Though difficult to fight from a distance considering his talent of evasion, Sonic is highly vulnerable at close combat.
Squirtle- Neutral, based solely on my experiences. From a tactical standpoint, you'd think Link would have the advantage- but in execution, it doesn't seem to be so. Maybe its because Squirtle's attacks aren't as weak as one might think from looking at him.
Toon Link- He's faster and his bombs have a wider radius. Both make up for what he lacks in power. Plus he can pretty much match Link's projectile game- despite the differences. Disadvantage to Link.
Wario- Slow, predictable, and easy to sword combo. Advantage To Link.
Wolf- Has a real reflector, powerful smashes, and can combo Link pretty easily. Disadvantage to Link.
Yoshi- Link can generaly outmanuver and out combo Yoshi. Yoshi's recovery has improved, but is still vulnerable. Advantage to Link.
Zelda- Can reflect projectiles, superior air game, and some unpredictable air Smashes. She gives me far more trouble in Brawl than she ever gave me in Melee- unlike Shiek. Disadvantage to Link.
Zero Suit Samus- Unlike her counterpart, Zero suit can dodge Link's projectiles and get in close to punish him. Disadvantage to Link.
There we go. Enjoy my opinions and such.
