Sub Zero (I edited the other because it was done in a rush...sorry for that

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In MK4 Sub is god tier. Why? Here´s a little rundown of his pros and cons:
Pros
-Without Wpn he IS a blue Scorpion. That means high priority normals and high priority combo openers. This means that most of the time you run at the same time that your foe (and assuming he has another char) Sub will gain the upper hand if both try to start a chain combo. Good aaHk that has high and long range. Long range Lk. Good aaHp´s and good Lp´s for stopping running foes on their toes. His early SUJK can be cancelled easily and is an important part of his rushdown as it has long reach.
-With Wpn he´s just plain evil. Sub can turtle/attack all day, mixing up stuff for not getting predictable. The Lp sweep is perfect and only a few chars can punish it if blocked. B+Hp is Juggle starter. B+Lp can freeze you and cannot be punished if blocked. Standing Hp has high poking priorities and can be an excellent aa. His jumpin´ attacks gain more priority so they are harder to Juggle, specially J.Lp. Back J.Hp is a nice aa too if done on reaction.
-Godly specials. The ice Clone is cheap. Plain and simple. It can be done very close to the foe and this can be very annoying. In a high level match against a Sub you MUST think twice every move you do, otherwise you will end up frozen. His Ice blast though slow off of a combo and with an 1 hit limit, is useful if you can hit confirm a close Hk (knee) then cancel with the Blast. The Slide is good for two reasons: First, it can punish EASILY all blocked sweeps and like 80% blocked weapon attacks. Second, it works very well as a transportation move (of course if it dont hit the foe). You can setup throw traps after a pop up combo or extend Juggles with it.
Cons
-Foes can duck without harm under B+Lp and Hp both Wpn attacks and can counterattack. Sometimes Reiko´s J.Hk can beat Wpn Hp. Liu, Reiko and Sub can punish almost all of his Wpn attacks.
-A blocked Slide means a 40% combo if punished correctly.
-Scorpion and Liu are the main weakness of Sub. Scorp can punish EVERY Ice Clone attempt with his Teleport Punch followed with the Spear for easy 47%. Liu Kang simply will not let him draw his Wpn by punishing every attempt to it with his Flying Kick. It also punish his Wpn attacks.
-All of his freezing moves activate damage protection so expect having a hard time trying to do damaging combos but this is relative because he has plenty of openings for freezing and with single hits alone he can dish out lotsa damage.
-As most chars, slow sweep speed that is easy to counter.
Basic tips and strategy
The main game for Sub is to get his Wpn out. So you should focus on setting this up as quick as you can. Some safe spots obviously, are when the foe is frozen. So we need first setups to freeze the oppnent. here are a few:
*Blocked chains works well, especially if you know that the Ice Blast lose his hit limit if the foe blocks. so we can do a 3-hit chain like HpHkLk and then cancel the tip of the Lk with an Ice Blast. It will come out fast because is part of a combo and the Lk is only fake and your foe may think that you messed up your chain and could go offensive. You can mix it up with the Ice Clone but both mix are useless against Scorp. Rayden can also teleport behind the Ice Blast but can get frozen if he tries to teleport behind the Ice Clone.
*You can also draw Wpn in any chain but the most safe is HkHk Drw Wpn. Why? If you know the game well then you know that you can punish every HkHk chain if you crouch block the first Hk then let Block off and the second Hk will whiff over you. You can here either get up and combo or just uppercutt your foe. Well, if you are Sub and you know your foe is waiting this then do it BUT cancel the second Hk with the Draw Wpn move. This causes a weird glitch in wich the foe CANNOT do any move except blocking, no matter how much he /she mash on any button. If he happens to block high both Hk´s he will be pushed away and if you did cancel the last Hk with the drw Wpn move he will "Stagger" in the block animation. This happens very fast and if the foe doesnt reacts in time, Sub will get his Wpn out and still be on the offensive. this can be punished with a quick special move but as said, it has to be done fast. This technique works for all characters but with differebt results due to the differents drw wpn attacks of all chars.
*After any sucesfull chain combo you can draw your Wpn. The most basic form is HpHpHkHk Drw Wpn. This allows for another hit in the form of the Slide or a J.Hp for more damage. If you feel just cocky, do HpHpHk, D+Hp, After the pop up Jum foward and do an instant Air Ice Clone. If done right you will freeze your foe airborne. Then you can simply draw your Wpn and wait for him/her to fall and keep Juggling. If you got down the early SUJK timing you can wait for the foe to fall a little after the Ice Clone then do early SUJK then B+Hp and follow it with anything you like, depending of course if you are in the corner.
Once you have your Wpn in hand the foe will realize that he is already in hell and will have to re-think everything he/she had in mind. Sub Standing Hp can punish various blocked attacks, mostly Wpn attacks and if blocked is hard to counter. Crossing your foe up with Wpn in hand is useful. Either if the opponent blocks or dont, you can cancel the J.Lp with an Ice Clone. if the opponent blocks its he will have to wait a little to see if you are going to do it or not. If he gets nervous and try to counter you he will get frozen, and in the worst case you will end up out of his reach ONLY if he/she isnt Scorpion. As mentioned, he can Teleport Punch you easily.
Quick Lp sweeps will keep them out of balance and will have to be in crouch block most of the rounds. Dont try blocked chains that include the B+Lp or B+Hp attack! The foe will just release block and uppercutt you! Instead go for the B+Hp or Lp sweep. Of course, again be careful against Reiko and Liu advanced players.
If you manage to get an B+Lp blocked, normally your foe will try to retaliate, this is the time for either an ice Clone or a close Hk into Ice Blast or better yet: Early SUJK , Hk, B+Lp. The Early SUJK has an awesome range and most of the time will connect.
Here is a list of basic combos that will take the most damage without much effort:
If your rival is on the the ground:
Without Wpn:
Hk, Ice Blast, SUJK, HpHpHkHk, Drw Wpn, Slide 9-hits 40%
Hk, Ice Blast, SUJK, HpHpHk, D+Hp, R.aaHp, J.HpHk 10 hits 42%
With Wpn:
Hk, B+Lp, SUJK, Hk, D+Hp, J.Hk, J.Hp 7-hits 36%
Early SUJK, Hk, B+Lp, SUJK, Hk, D+Hp, J.Hk, J.Hp 8-hits 44%