Basic Moves:

Moves that require only a button press:

HIGH PUNCH - Produces a punch to the face. Many can be strung together in succession by rapidly pressing  the  button.       
LOW PUNCH - Your character will punch the opponent's midriff. Many can be strung together in succession by rapidly pressing the button. Not as powerful as a high punch but can hit the opponent while they are ducking.
HIGH KICK - Smacks your opponent in the face with a powerful kick
LOW KICK - Not as powerful as the high kick but a little faster to recover, kicks the opponent in the abs.
BLOCK - Blocks attacks            
RUN - Lets your character runs forwards for a limited amount of time. This is great for attacking opponents who are running away from you. Pay attention to the run meter (the smaller meter underneath your health bar) - this will indiciate how long you can run for.
SIDESTEP INSIDE - This takes advantage of Mortal Komabt Gold's 3D battle arenas, and is useful for dodging projectile attacks or disorienting your opponent slightly before attacks. This steps TOWARDS the screen.
SIDESTEP OUTSIDE - Exactly the same as sidestepping inside except you sidestep AWAY from the screen.
    
Combination Moves:

Moves that require a button to be pressed simultaneously with a direction:  

Jump Kick - Jump + either KICK button.    
Jump Punch - Jump + either PUNCH  button.         
Pressing up plus kick or punch will result in your character punching  or kicking in midair without moving in a direction. If jumping  towards or  away from the opponent, pressing punch or kick will cause your  characrter  to extend their limb a little further to hit the opponent and  will cause more damage. A Jump Kick is more powerful than a Jump Punch, but  Jump Pucnhes are better for winning aerial battles.      
Uppercut - Down + HIGH PUNCH.
The Uppercut has lost a lot of it's firepower in MK Gold...it is nowhere near as powerful as it is in the 2D Mortal Kombats. It still serves a purpose though.
Sweep - Back + LOW KICK      
Sweeping knocks your opponent onto their back by tripping them over.   
Roundhouse - Back + HIGH KICK
Your character spins around and gives your opponent a heavy kick to the side of the head, causing them to spin through the air.
Weak Kick - Down + LOW KICK
Not really useful unless your opponent is ducking and avoiding your other attacks...weak and slow.
Throw - Forward + LOW PUNCH
Must be standing right next to your opponent. Different characters throw in different ways, but all throws do good damage. Throws cannot be blocked normally.
Bone Breaker - Forward + LOW KICK
Perhaps your character's most potent move, the Bone Breakers are a painful addition to Mortal Kombat 4 and Mortal Kombat Gold. Executed in similar fashion to a throw (you need to be up close to your opponent), they deliver damaging hits to your opponent. Different characters have different Bone Breakers, each with varying damage. Some leave your opponent open to be hit again. Like a throw, they cannot be blocked normally.
Block Throw/Bone Breaker - BLOCK + diagonally down + away
Pressing down and away while blocking will prevent your opponent from executing a throw or a bone breaker.
Power Hit - Forward + HIGH PUNCH       
Some characters elbow, some headbutt, but the basic premise is the same - a strong hit to the opponent in close quarters. Most characters can perform a two-hit combo by pressing HIGH PUNCH twice.
Attack with weapon - Forward OR Back OR Down + HIGH PUNCH or LOW PUNCH
Your character must be holding a weapon to be able to execute these moves, and what your character does depends on what weapon your character is currently holding. Experiment, especcially if you pick up a weapon that isn't your own.

Special Notes:

Mortal Kombat Gold is more or less an extension to Mortal Kombat 4 (much like Ultimate Mortal Kombat 3 was to Mortal Kombat 3). It is essentially the same with extra characters and battlegrounds thrown in. Baraka, Kitana, Cyrax, Kung Lao and Mileena are now readily selectable, with a few more hidden characters. It was a special edition exclusive for the Sega Dreamcast.

For other information refer to the Mortal Kombat 4 FAQ...the same concepts apply here.

I will not repeat myself and mention the characters here that also appear in Mortal Kombat 4 - refer to the MK4 guide if you are after the moves for those characters. Instead, I will only list the new characters that appear in Mortal Kombat Gold.

Character Weapons:

Below is a list of the different weapons available in the game for the different characters:

Cyrax - Light Sword
Mileena - Crooked Sword
Kitana - Blade Boomerang
Kung Lao - Diamond Axe
Baraka - Bone Axe

Special Moves:

BARAKA

Weapon: Back, Back + Low Punch
Blade Swipe: Back + High Punch
Blade Spark: Down, Back, High Punch
Double Kick: Press High Kick twice quickly
Blade Fury: Back, Back, Back, Low Punch

Fatality 1:  Back, Back, Back, Back, High Punch (close)
Fatality 2: Back, Forward, Down, Forward, Low Punch (sweep)
Fan Fatality: Forward, Forward, Down, High Kick
Spike Fatality: Down, Back, Back, Low Kick

KUNG LAO

Weapon: Back, Back + High Punch
Hat Throw: Back, Forward, Low Punch
Teleport: Down, Up
Spin Attack: Hold Block, Up, Up, Low Kick
Torpedo Kick: Down + High Kick in the air

Fatality 1: Back, Back, Forward, Low Punch (sweep)
Fatality 2: Forward, Forward, Back, Down, High Punch (past sweep)
Fan Fatality: Down, Down, Forward, High Punch
Spike Fatality: Forward, Down, Forward, Low Kick

MILEENA

Weapon: Forward, Forward + Low Punch
Sai Throw: Hold High Punch for 2 seconds, release 
Teleport Kick: Forward, Forward, Low Kick
Roll Attack: Back, Back, Down, High Kick

Fatality 1: Back, Back, Back, Forward, Low Kick (sweep)
Fatality 2: Forward, Back, Forward, Low Punch (sweep)
Fan Fatality: Forward, Forward, Back, High Punch
Spike Fatality: Down, Forward, Down, Low Punch

CYRAX

Weapon: Back, Forward, High Punch
Net: Back, Back, Low Kick
Short Bomb: Back, Back, High Kick
Long Bomb: Forward, Forward, High Kick
Teleport: Down, Forward, Block (can do in air)
Air Throw: Forward, Down, Block (Low Punch to throw)

Fatality 1: Hold Block, Up, Up, Forward , Down , release Block then press Block again (close)
Fatality 2: Hold Block, Down, Down, Forward, Up, Run, release Block (sweep)
Fan Fatality: Back, Forward, Forward, High Punch
Spike Fatality: Down, Back, Back, Low Punch

KITANA

Weapon: Forward, Back + High Kick
Fan Throw: Forward, Forward, High Punch + Low Punch
Fan Swipe: Back + High Punch
Fan Lift: Back, Back, Back, High Punch
Teleport Punch: Down, Back, High Punch

Fatality 1: Back, Down, Forward, Forward, High Kick (close)
Fatality 2: Forward, Forward, Down, Forward, Low Punch (close)
Fan Fatality: Forward, Down, Forward, Low Punch
Spike Fatality: Down, Down, Forward, Low Kick

Secrets:

Kombat Kodes

See the MK3 guide for explanations on Kombat Kodes

111-111:Free Weapon
123-123:No Power
222-222:Random Weapon
012-012:Noob Saibot Mode
321-321:Big Heads
020-020:Red Rain
444-444:Armed & Dangerous
050-050:Explosive Kombat
555-555:Many Weapons
002-002:All Time Weapons
666-666:Silent Kombat
100-100:Disable Throws
010-010:Disable Max Damage
001-001:Unlimited Run
110-110:No Throws & Max Damage
011-011: Goro's Lair
022-022: The Well
033-033: The Elder Gods
044-044: The Tomb
055-055: Wind World
066-066: Reptile's Lair
101-101: Shaolin Temple
202-202: Living Forest
303-303: The Prison
313-313: Ice Pit
323-323: The Church
343-343: The Netherealm
353-353: Soul Chamber
363-363: Ladder Stage

Other Secrets

Cheat Menu

During the screen where it says "Mortal Kombat Gold Press Start" Press Up, Up, Down, Down, Left, Left, Right, Right. You should then hear "Outstanding". This must be done fast to work. Then press Start and hold both L/R Buttons to access the cheat menu.

Fight as Goro

Enable the Cheat Menu. When you get to the Character Select Screen go down to "Hidden" and Select this by pressing and holding both L and R Buttons. Then go and select Shinnok with the A Button.

Fight as Meat

Play a 2-Player game, and have both players select group mode. One player must get 20 wins in a row. After the last character in Group Mode has been completed, Meat will take the place of your chosen character. Meat uses the same moves as the character you selected previously.

Fight as Noob Saibot

Enable the Cheat Menu. When you get to the Character Select Screen go down to "Hidden" and select this by pressing and holding both L and R Buttons, Then go and select Reiko with the A Button.

Fight as Sektor

Enable the Cheat Menu. When you get to the Character Select Screen go down to "Hidden" And select this by pressing and holding both L and R Buttons, Then go and select Cyrax with the A Button.