Showa Godzilla

Height: 50 meters
Mass: 20,000 metric tons

Strengths:
Able to press roughly 150,000 metric tons, and an extraordinary jumper due to this (his jump ceiling is unknown, but it's probably hundreds of meters)
Nearly inpenetrable hide
High pain tolerance
Can see in infra-red
Able to run at 40 kilometers per hour
Able to swim at 40 knots
Remarkably fast reflexes
Human-like intelligence
Able to sense danger instinctually
Probably mildly telepathic

Powers
Able to fire a 100,000 degree Incandescent Ray of super-heated air from his mouth
Able to fire a 250,000 degree Radioactive Blaze Ray of nuclear flames from his mouth.
Can fly at Mach 1 with high-pressure air breath
Electro-magnetic pulse
Super regenerative power

Fighting Moves:

Swipe: Godzilla swipes with his claws, and possibly his most commonly used fighting move, especially against Anguirus
Punch: The same punch that gave Hedorah and Mechagodzilla something to fear
Bite: The same bite that crushed Anguirus' throat
Kick: A rarely seen move, this is actually most often seen for launching rocks.
Jump-kick: Godzilla can jump up and use both feet to knock an enemy down.
Tail-Swat: Godzilla's defense against King Kong and the Mothra Larvae
Grapple: The same grapple that ensnared King Ghidorah
Face slam: Godzilla can grab an enemy by the tail and lift them up and down.
Flying kick: The impossible move that finished Megalon
Lift-Toss: Godzilla can pick up enemies and throw them, as he nearly did to Titanosaurus.
Stomp: When an enemy is down, Godzilla will trample the enemy, as he did to King Ghidorah
Body-slam: Godzilla slams into an enemy with all his body weight and momentum.
Rock-toss: Godzilla's not above using tools, and would gladly use rocks for both long-range and short range combat

General Fighting style: High emphasis on speed, very bestial at times, also fights a lot like a sumo wrestler and a boxer.

Weaknesses: Weak against electricity, probably is vulnerable in major regions of his nervous system, being the brain and spinal chord, and is also probably vulnerable in the main nuclear reaction system, which has replaced his digestive system.

Advantanges for this specific match: Superior physical strength, astounding speed fighter, regeneration, radiation might interfere with his opponent's electro-magnetic heart, possibly superior durability.
Disadvatages for this specific match: Slower movements, weapons will probably be useless, inferior intellect, inferior agility, regeneration and hide will likely not be enough against Ultraman's weapons and strategies.

Personality: Strange to say, Godzilla is usually quite peaceful, often not starting fights and only getting into them when provoked. When provoked, however, he can be extremely tenacious and prone to taking tremendous risks just to get that much closer to winning, but rarely ever kills his enemies, even when he has the chance to. Death wish much, Godzilla? He will, however, sometimes loose his temper and unleash his weapons and skills at their fullest potential, which can result in the death of his opponent.

Original Ultraman

Height: 40 meters
Mass: 35,000 metric tons

Strengths:
Able to press 200,000 metric tons and an extraordinary jumper due to this (jump ceiling is 800 meters)
Difficult to sneak on him due to super-human senses and compound eyes
Can see in nearly all spectrums
Nearly unbreakable armor made of an organic space-metal (explaining the mass)
Able to run at 450 kilometers per hour
Can swim at 200 knots
Able to fly at mach five
Innovative combatant
Super-human intelligence
Almost completely immune to nearly all energy attacks (unless it radiated enough energy to roughly 1 million degrees or could completely disintegrate an object).
Almost certainly moderately telepathic

Powers:
Missile-strength Spacium Ray, which can either cause kaiju combustion or disintegrate kaiju and rematerialize them elsewhere.
Ultra Slash that can cut through stone-tough kaiju; it has decapitated numerous kaiju.
Slash Ray can cause missile-strength explosions and cut through kaiju.
Ultra Air Catch: Ultraman can catch his enemies and keep them completely frozen and suspended in the air for a short time; this makes them more vulnerable to his attacks.
Anti-Gravity Ray: Ultraman can lift his enemies far into the air before dropping them, an attack of its own.
Ultra Barrier can temporarily withstand all attacks,
Ultra Shower can launch water from his hands,
Flouroscope ray can let him temporarily see all spectrums,
Ultra Discernment can narrow down the spectrums he sees in to concentrate on something
Teleportation
Ultra Attack Ray is all of his energy mustered from his body, and is possibly his most powerful weapon
Ultra Rings can completely hog-tie his enemies
Telekinesis

Fighting Moves:
Air Body: Ultraman rams the opponent with his body in mid-air. His body does not seem to suffer any ill effects from the collision.
Ultra Headbutting: Ultraman hits the opponent with the top of his head, it is said to be a hundred times harder than diamonds.
Ultra Chop: A basic chop, there is a variation called 'Ultra Sword Haze', where Ultraman slices the opponent as he passes, this was used on Jirass.
Ultra Punch: A punch skill to assess the weaknesses of the enemy. Said to have the power of fifty charging elephants.
Ultra Kick: A kicking technique using concentrated power in the legs. It is several hundred times stronger than what would be expected from his stature.
Dive Kick: A double kick from high altitudes. Used on Greenmons, Red King, Gomora and Geronimon.
Rotate Neck Tighten: Strangles the opponent with his feet, similar to a wrestling move. Used on Dada.
Ultra Swing: Grabbs the opponent and throws them.
Dropped Rock: Lifts the opponent into the air and slams them into the ground.
Flying Mare: Grabs the opponent by the neck and throws them. Used on Red King and Telesdon.
Monkey Flip: When faced with a charging opponent, Ultraman grabs them, falls on his back and uses the opponents momentum and his leg to flip them over.
Neck Hanging: A technique where Ultraman holds his opponent by the neck while lifting them. When his foe is weakened he throws them.
Headlock: Ultraman headlocks his opponent to seal their movements.

General Fighting style: Heavy emphasis on strength, very controlled and martial arts-like, often reminiscent of Judo, alligator wrestling, and Greco-Roman wrestling.

Weaknesses: Can only fight for a limited time, typically about three minutes (can be slightly more or slightly less depending on how much damage he takes or how much energy he spent on his powers), due to the lack of viable energy to consume on Earth, cannot teleport too often because of the debilitating effects it has on him, low pain tolerance.

Advantages to this specific match: Superior intellect, superior agility, superior movement speed, weapons will probably be effective, probably immune to his opponent's weapons.
Disadvantages: Weaker physical strength, possibly inferior durability, time limit, opponent's radiation might interfere with his electro-magnetic heart, sparing with energy weapons due to limited energy supply.

Personality: He's also actually quite peaceful, and hates fighting two thirds of his enemies, because they are animals. He loves animals but often has to reluctantly fight them to the death anyway; his enemies rarely ever live after fighting him, though he shows his respect by rarely ever attacking from the back and also for giving them a moment of respectful silence after each death; this is the sort of guy that would require therapy for post-traumatic stress disorder due to all the lives he had to take, just like some American soldiers. He still maintains a great sense of humor and likes to tease his opponents into making stupid mistakes.

These are two of the most powerful and two of the bravest super-kaiju of their eras: WHO WOULD WIN A DEATH BATTLE?!

Money's on Ultraman if he can deploy Ultra attack Ray

4602366
I think you're right, or at least, the choice over who wins and who loses boils down to Ultraman. Godzilla consistently tries to fight at close range, so ultimately Ultraman's choices would be the deciding factor. If Ultraman chose to fly or stay at a distance, it would be all over for Godzilla. If Ultraman chose to fight at close range, the result would be more ambiguous. I need to revise this a bit, I was wrong about some things.

The more interesting is Gudis vs Godzilla, in the end either Godzilla wins or he becomes a Gudis slace.