Differences from MK3
Can no longer perform infinite combos in corner, Single and Double Fireballs have longer recovery.
Move List
Basic Moves
Shang's basics are kinda mixed. He definitely has a sluggishness about him in general, but that's really only his ground combos. They have significant pauses in them that result in breaks constantly. However, his uppercut, standing HK, and RH are ideal anti air attacks, and your choice is up to you or the situation. His uppercut's range and height is excellent, however during his duck and rising frames he tends to get stuck, so aaUppercuts need to be anticipated a little sooner, or you have to wait just slightly to allow their jump attack hit duration to pass. Kano and Nightwolf will often times snuff his uppercut so it's better to go for the standing HK which is high and pointy, his RH is also high with good range. Sweep range is a little less than to be expected. Stand LK is good, his ducking LK is also good. A lot of his basic moves are similar to that of the Male Ninjas. His run jab game is decent, sometimes you can try and stick in a single fireball after a few run jabs. His JK is very good, his JP is ok. His straight up JK is pretty nice.
Special Moves
Flaming Skulls
Single B, B, HP
Double B, B, F, HP
Triple B, B, F, F, HP
8%
The Flaming Skulls (fireballs in the general gaming world) have existed since MK1, but in MK3 they were changed significantly. They were originally small and fast moving, now they are slower, and longer. You may notice certain fireball amounts are better for different set ups and combo opportunities. Double fireballs are a good bet, Shang seems to recover quickly after them compared to the height they usually bounce off the last one. If you do 3, the 3rd might not hit them right and Shang winds up unable to capitalize, so stick to usage of 1 or 2. Fireballs have no limit of usage, and no pre set hit limit when they turn off, you can stagger their usage by placing two hits inbetween them, much like Stryker's riot gun. For example: in corner, aaHP,HP, double fireball, JK, aaLP, double fireball. This is not a conventional in game combo, but it demonstrates the moves limits. Try to stick in single fireballs anywhere it's safe if you're not going for morph game, the situations are similar, like after a roundhouse, or throw.
Ground Eruption
F, B, B, LK
5%
The Ground Eruption (GE) is a very interesting move, similar to his fireballs, but sets up free juggles if they connect. Mix up cross patterns of single or double fireballs and GEs in effort to lock your opponent down, watch for their move, pin them down, keep them guessing, keep it constant, don't let up, and ultimately set up GE combos. Another great thing about the GE is that it's a free morph opportunity as well, and you can set up great juggle combos off them easily, but pulling them off is up to your own abilities. The GE has absolutely no limitations whatsoever and can be continually used over and over with no break inbetween, setting up difficult, but doable infinites. Remember in order to really benefit from the juggles, the GE has to hit the characters well placed. If you do one from full screen as Jax is about to do his missile, chances are the third will GE will miss so you will need to watch for this and compensate combos. Against non teleport characters sometimes it's a good idea to do two GE's in a row, because they will often times run through the first two and get hit by the third, as they go up on the third, RH them into the following GE. Most characters will get juggled by all three GE's from a full screen distance, Robots, Female Ninjas, Shang, Sheeva, Kabal, Sindel, Sonya, Kung Lao, Liu Kang, some (Stryker and Male ninjas) will only get hit by one, the rest get hit by 2, so set combos up accordingly. In order to get the full juggle you have adjust the distance slightly, but generally there is not enough time to do this so you need to pay attention to where they get hit. This really only applies to grounded opponents.
Morphs
1) Liu Kang: 360 Circle (Hold Block)
2) Kano: B, F, BL
3) Sonya: D + RUN + BL + LP
4) Kung Lao: RUN, RUN, BL, RUN
5) Kabal: LP, BL, HK
6) Sindel: B, D, B, LK
7) Cyrax: BL, BL, BL
8) Sektor: D, F, B, RUN
9) Nightwolf: U, U, U (Hold Block)
10) Jax: F, F, D, LP
11) Sub-Zero: F, D, F, HP
12) Stryker: F, F, F, HK
13) Sheeva: F, D, F, LK
14) Kitana: F, D, F, RUN
15) Scorpion: D, D, F, LP
16) Reptile: RUN, BL, BL, HK
17) Jade: F, F, D, D+BL
18) Mileena: RUN, BL, HK
19) Classic Sub-Zero: BL, BL, RN, RN
20) Ermac: D, D, U
Morphs are probably his best tool overall because of versatility and strategy changing at your command. If you know how to use a lot of characters, you might like playing as Shang just for the challenge of being him at certain times. Morphs last approximately 16 clock seconds in 1 on 1 gameplay and have no limit of usage. Keep your characters varied, look for free morph situations. Generally after a RH, or especially an anti air RH, a morph is free, so have an idea of who you would like to use in those situations. Uppercuts have a reasonable amount of morph safety, as do juggle Fireballs, and the GE is obviously the safest. It is possible to use morphs to cancel corner push back and possibly continue combos, but you have to make sure you are paying attention to morph times.
Shang has a few variations of the same infinite using his GE. The easiest way is to start with one hitting all 3 fireballs, then run Shang to the middle and do another, as the character hits the last fireball which goes up just behind Shang, he will be hit into the second fireball from the second ground eruption, getting knocked back over in front of Shang. Repeat this as much as you like til you get to a wall. It's also possible to knock them the other way into fireballs coming up from behind in a similar manner, but doing the GE a bit late. Another way to do it, is if the person jumps onto the first GE, run almost to the other side of the screen and GE as they are landing. You have to make sure the last hit knocks them behind you, so walk into the middle, let it hit them over, then run and buffer the next GE to hit as they fall.
Finisher Moves
Fatality 1
Hold LP, D, F, F, D, Release LP (Next to)
Shang raises his hands and spikes come out of the ground. Then he lifts the victim and slams them into the spikes.
Fatality 2
Hold LP, RUN, BL, RUN, BL, Release LP (Next to)
Shang raises his hands to the air and his victim rises into the air. when in the air the soul gets pulled out of the body of his victim and the body falls into a pile of green glob and Bones.
Friendship
LK, LK, RUN, RUN, D (No Block in Winning Round) (Past Sweep)
Shang turns into a little creature from JOUST and bounces away.
Animality
Hold HP, RUN, RUN, RUN, Release HP (Mercy First) (Sweep)
Shang turns into a big green viper which then eats his victim whole.
Babality
RUN, RUN, RUN, LK (No Block in Winning Round) (Past Sweep)
Mercy
Hold RUN, Wait 1 Second, D, D, Release RUN (Round 3) (Past Sweep)
Stage Fatal
U, U, B, LP (Next to) (Hold Block)
Strategy
As Shang Tsung
Shang Tsung is a low tier character, near the bottom, perhaps in the 20s, but the fact that he has an infinite at his disposal and large easy morph combos off a single ground eruption, with some effort means he cannot be last even though basically he is less capable than most. Shang's lock down, keep away, and zoning pressure can be absolutely insane if you commit to a gameplan with him. Your strategy is going to be constant double fireball to ground eruption traps and set ups. His ground combos are limited, no pop ups, significant recovery time on his comboed roundhouse, etc. Remember, if you are Shang Tsung, you are also, at limited durations, Kabal, Kung Lao, Kano, Ermac, etc. If you mix these characters up with others like Reptile and Kitana who have completely different strategical defense, you'll have your opponents guessing, and adapting constantly. It is theoretically possible to beat people without morphs just using his lock down and basic moves, because the important ones are good. His collision boxes are the most awkward and unique in the game. Many juggle combos simply do not work on him, so take notice that people will have to significantly modify combos on him, generally doing a lot less to him. This is an advantage against some characters. Also, he has a hard time ducking certain projectiles if you're a hair late, watch out for this.
VS Shang Tsung
Combos
Basic Juggles: 
1. aaHP,HP, double fireball 4 hits 28% (sets up GE lock down or if they jump as soon as they land they will get hit and it sets up juggles, morphs, and infinite combos) 
2. GE, aaHP,HP, double fireball 7 hits 43% 
3. (near corner) aaHPHP, double fireball, uppercut 5 hits 50% 
Advanced Juggles: 
1. aaDouble Fireball, GE, aaHP,HP, aaHP, double fireball, 10 hits 65% 
2. (near corner) aaHPHP, double fireball, JK, HK, 6 hits, 59% 
Morph and GE related Combos of various degrees of difficulty: 
1. aaDouble Fireball, [Ermac], teleport punch, aaHP, Lift, aaHPHP, aaHP, fireball 8 hits about 47% 
2. aaLP,(BL,HK for Kabal morph) spin, aaHP,HP, JK, air fireball (JK on some) (and now you are safe as Kabal to terrorize for about 12 clock seconds) 6 hits 47%-48% 
3. GE, [Kabal] aaHPHP, JK, air fireball 7 hits 57% 
4. GE, [Jax] aaHPHP, JK, air throw, 7 hits 59% 
5. GE, [Nightwolf] Axe X4, aaHP, Axe, aaHP, Shoulder Tackle 11 hits 60%(varies on the characters, for example against Kabal, Sub Stryker or Jax, the full combo isn't that difficult, but against Shang it would be impossible)
6. GE(2 hit), [Sindel] scream, aaHP, scream, aaHP, scream, HK, HP, HP, D HP, aaHPHP, JK, air fireball 12 hits 69% 
7. GE, [Ermac] JK, Lift, aaHPHP, aaHP, fireball (JK on some) 8 hits 67-71% 
8. GE, [Liu Kang] aaHPHP, JK, Air Fireball, Dragon Kick 8 hits 70% 
9. GE, [Reptile] - as many aaHPHP whiff elbow dashes, as possible on whatever character you're against, for example, GE, [Reptile] aaHPHP, whiff dash X3, uppercut, 10 hits 75% 
10. GE(2 hit), [Ermac] aaHP, JK, lift, aaHPHP, aaHP fireball or JK 8 hits 68-73% 
11. GE, [Kung Lao] into various spin, or aaHP, JK, whiff dive kick infinite combos 
12. [when aware of being Sub for a while] aaHP, freeze, or aaFreeze, aaHP, freeze (kill whatever time is necessary) [Shang][Kung Lao] to infinite variations or Ermac and anyone of his various ridiculous combos.