Ok ok ok! I get it...stoping with the up-B now I promise...
Good, that saves a lecture.
First thing I took notice of is that you don't use your shield at all, and you don't move. You kind of sit there and wait for Sheik to nail you with dash attacks.
I also noticed that while he was transforming, you simply let him do it. Why not tank him right there and then? You could've gotten off a fair amount of damage before he even had a chance to transform.
Second thing I saw, a lot of poorly placed boomerang shots. The boomerang is a powerful weapon, great for control, but you have to know when, where, and how to use it. It's also a good idea to throw it in the direction you think opponent will try to dodge it. One of my favorite tactics is to throw the boomerang up, or down so it ricochets up, and let the opponent jump their face right into it, which leaves me open for a shffled fair.
Good timing with all projectiles,
including bombs, is an absolute
must for link. If you can't hit them with that arrow when you're falling, then it only serves to make you that much more vulnerable.
You roll far too much, and your rolling is
very predictable. Any decent Sheik could've chain grabbed your nuts off with the way you roll. Roll sparingly, and when you do, make absolute sure that you won't be caught by the opponent, bad rolls = major punishment.
Wavedashing and L-canceling are two fundamental techniques you need to learn, and fast, if you ever plan to kill this Sheik. Though WDing won't make the game for you, it makes shffling much quicker and can be used for mind games. And L-canceling will save your *** loads of times and allow you to use your all powerful Dair with less repercussions on a botched attempt.
Use your grab ONLY when you know your opponent can't get away! There is no way to cancel your grab if you **** it up, and that leaves you open for some serious Sheik rapage. A good time to use your grab is when you shield. Say a Sheik comes after you with a dash attack and it doesn't go through because you shielded, press A while shielding and grab the mofo. Get an little hits off that you can, dthrow, utilt, bair, etc, etc. Link has some badass combos, but you need to learn the techniques to use those combos effectively before you can try them in a real battle.
NOTE on that last pragraph: Watch out for Sheiks dash attack, it will sometimes send her through and behind you, hence eliminating chance for a grab, even if you shielded, You could try anything from a dsmash (very effective), to a spin attack BUT ONLY AT VERY HIGH PERCENTAGES!
Which brings me to another point.
Learn to crouch cancel. Sheik practically
depends on knocking you into the air or dash attacking to stun you at low percentages in order to rack up the damage. Crouch cancel that dash attack they all love and cherish and while doing is eat them alive with dtilt or dsmash to set up a combo! This is a wonderful little toy that pisses all of my Sheik friends off. If they can't get me in the air, I can control them more effectively with my boomerang or bow.
NEVER LET A SHEIK GRAB YOU! If they learn how to chain grab, you could very well be stuck for a long time. If you can't DI out of a chain grab, some Sheiks will CG you up to over 100% damage, which sets you up for easy and deadly Sheik tilts.
Use your sex kick! This is your neutral air attack, when you just press a in the air. Shffl that on this Sheik, and they're likely to get pissed! Your nair is probably your best weapon because it has great priority and it also is ****ing great for intercepting a recovering Sheik.
This Sheik you're playing isn't very good, I'd annihilate this Sheik, but that's because I have more experience. Keep practicing, and try to learn to react to they the opponent moves. This makes defense easier and offense much better.
Also, I don't if you are or not, but if you want a good and fast link, you better start using that c-stick for your smash attacks and aerials.
And last but not least, I will remind you that you need to learn how to
shffl,
wavedash,
L-cancel, and
aim those beautiful projectiles you have sitting at your finger tips!
Practice, practice, practice. Any good Link player will tell you that to yield results with beast that Link is, you have to practice a lot, and of course with humans more so than anything.