I'm not going to go over the exact map routes here, I recommend viewing somebody's run and learning them there.

Mashing text

I slide my thumb across the four face buttons as fast as I comfortably can. L and R can be pressed as well.

End stage screen

On NA you can just hold A to automatically rush through the score screen, no need to mash. On J you hold Start instead.

Fighting spirit/biorhythm

Godzilla and every enemy has a fighting spirit meter at the top of the HUD in the battle menu. For Godzilla, the meter determines what attacks you will be offered after you land a punch. For the enemy, high spirit generally means a high chance of them initiating a cutscene attack on you, wasting exorbitant amounts of time. Godzilla's fighting spirit raises when you walk forward and lowers when you block or don't move forward for a while. The enemies fighting spirit goes up when you walk forward as well, exponentially increasing the longer you hold forward. It's generally a good idea to release forward after half a second or so unless the enemy's spirit is no longer a concern. The enemies fighting spirit when you land your punch matters as well, if their spirit is high you'll generally have less time to select an attack and the attacks you select will do less damage. After you land an attack every boss has a chance to counterattack, with their fighting spirit spiking violently followed by them charging you. This becomes more likely as their health gets lower. Learning to manipulate your own fighting spirit is important if you want stronger attacks, and quicker fights.

Blocking

Hold down to block. This will prevent an enemy from cutscene attacking you, memorizing and reacting to enemy biorhythms and blocking when their fighting spirit spikes is integral to quick and safe fights. If an enemy bumps into you shortly before their fighting spirit spikes they can force your guard down and cutscene you. This is most prominent with Bagan, but it can happen against any boss if you're in a bad position.

UFOs

They will attack you periodically starting in stage 2 unless the mother UFO is dead. As normal Godzilla walk up to them, ram into them once, punch them, then continuously ram into them until they're dead. If you're extremely damaged (<30-50 hp) you could fire breath them to avoid damage but it's slow. Usually only really needed if you're on very low HP after a Battra fight. Every UFO encountered costs between 17-18 seconds, so they have a huge impact on your final time.

Super Godzilla Super Punch

Damage and distance traveled scales with how long you charge it. A slightly charged punch will kill a UFO in a single hit.

Stage 1

The goal is to rush straight to King Ghidorah and defeat him. Immediately when the map starts look at the enemy distance counter. If it is 288, he spawned one map over to the right. If it's 368 he spawned in the top right map and you should reset.

King Ghidorah

A simple and effective strategy for King Ghidorah is to immediately rush in and punch him, then back up enough to get one attack and walk back in a bit before executing the attack. From this point you repeat this over and over until he's dead, punch, back up, walk forward, attack. This keeps him "stun locked" and will prevent him from cutscene attacking you if you're quick enough. It's possible to get faster times by manipulating fighting spirit to get stronger attacks but I generally like the safe strategy. The more runs you get past King Ghidorah, the more often you'll get past the scientist spawn in Stage 3.

Stage 2

You need to kill the mother UFO or Mecha-Godzilla will warp away from you. After it's dead, rush to Mecha-Godzilla.

Mother UFO

The goal here is to land a punch and ram them, just like a regular UFO, only the Mother UFO can fly up out of reach and will only come down after you return to the left half of the screen. I find the fastest strategy is to just charge forward any time they're down and go for the punch. Once you land a punch, their fighting spirit will spike and then plummet. The amount of damage you do and receive is based on their fighting spirit. The best strategy is to punch them every time their fighting spirit plummets to keep their fighting spirit low and reset the pattern. Even if the Mother UFO flies up and away from you a few times the time for this fight generally balances itself out because you'll have more spirit and do more damage when you finally land a punch.

Mecha-Godzilla

A simple and effective way to handle this fight is to learn Mecha-Godzilla's biorhythm and use it to land Super Breath. Mecha-Godzilla's biorhythm is as follows: one medium pulse, one high pulse, then four gradual increases followed by a drastic drop. Holding forward against Mecha-Godzilla increases his fighting spirit, and if his fighting spirit peaks during any of this pattern he will charge and possibly cutscene you. Start by waiting for the medium and strong pulses. After the strong pulse shuffle back and forth in small motions to build a bit of spirit during the first three pulses of the gradual increase. Stand still during the fourth increase, then charge all the way forward, punch, and select Super Breath. Block if they counterattack, then repeat. If they don't counterattack you can do what I call fast breath, if your Super Breath was 2-4 cards back you should have enough distance to build spirit and land a punch in between the medium and high pulses. If done properly these can be chained together until Mecha-Godzilla counterattacks.

Stage 3

The big reset. You need to find the scientist to spawn Biollante, the only problem is he spawns in one of six random locations. Head to the closest possible location and if he isn't there, reset. It sucks. If you're not concerned with losing ~3 minutes, you can check the yellow info box in the top left of the map 2-B and it will show you where he really is. Once you find him, head to the top left map and he will have spawned in the water there. Keep track of the direction Biollante went last when you first initiate the fight. When you escape from the fight, head in that direction in case Biollante tries to make you chase him around the map for 45 seconds.

Biollante

We use a glitch to make this fight a cake walk. When she spawns she will have two feelers you're supposed to destroy before you can begin the real fight. The funny thing is, if you destroy only the feeler in the back, then escape from the battle, the game enters this weird state where it thinks the feelers are both dead when one is still alive. From there it will let you simply walk through the feeler and punch Biollante for free. It can be confusing to remember which feeler was the back one. If you lose track or you're not sure, pay attention to which feeler is layered in the back when they're on top of each other. That is the back one. Manipulate your fighting spirit to get super fire breath every attack and spam it. There is a chance when you return to the fight that the glitched feeler will come back from off screen to the left and unbug the fight. It's rare, but if it happens just escape and try again.

Stage 4

Pick up an energy capsule and two fighting spirit capsules, and walk across the mines to the top right to get to Battra. Once Battra is defeated the stage doesn't end until you go back to the left and possibly down and find the larva. Godzilla will automatically destroy it and end the stage.

Battra

This fight has a decent amount of luck. You're going to be low HP from walking across the mines, so use your energy capsule. Then pop a fighting spirit capsule and hold right and ram into Battra until your fighting spirit is high and you can land a punch. Super fire breath is the only attack that can hit Battra so make sure you get it. After landing an attack, pay attention to Battra's fighting spirit and whether he was in the sky. If it's shaking violently while slowly rising it's about to spike and you'll get attacked if you don't block, unless Battra is currently in the sky in which case just hold forward. Other than that just keep holding right and landing punches, use your second fighting spirit capsule when the first one runs out. If things go well you'll only need two. If Battra wastes enough of your time and your capsules run out, you'll need to try to build spirit while blocking when Battra's spirit spikes.

Stage 5

This map has the longest path to memorize, and memorize it well because if you don't move through it efficiently too much of the city will be destroyed and you won't have access to Super Godzilla in the final stage, effectively losing you three minutes. The goal is to grab all three Super Godzilla stations and get to Mecha-King Ghidorah while destroying as little of the city as possible. This means you'll retrace your steps you took to get the three stations as well as taking a path past the future spawn of the Stage 6 Super Godzilla station and walking on the land mines to avoid destroying buildings. The destruction is dependent on where Mecha-King Ghidorah decides to walk, if he decides to go on a destruction spree even optimal routing won't save you. As if you needed more luck this far into the run, right? The chance for city destruction can be bypassed entirely by doing Mecha-Ghidorah as regular Godzilla, which is faster and more difficult.

Mecha-King Ghidorah (Super Godzilla)

This fighting is interesting in that optimally you don't see a single cutscene attack from either side. Start off the battle with a nice long charged Super Punch and then hold right to ram into Mecha-King Ghidorah. From here you're going to spam Super Punches while holding right to ram. You have to be efficient here or you'll take too much damage from ramming and die before Mecha-King Ghidorah. You can't buffer the punch, but you can hold down a face button and mash other face buttons to have it charge despite your mashing. I hold right with my left thumb and Y with my right index finger while mashing X and A with my middle and ring fingers and then release Y, X and A to unleash the charged punch. With effective mashing you can easily end this fight with over 200 HP.

Mecha-King Ghidorah (Regular Godzilla)

Mecha-Ghidorah is very reactive to aggression. Holding forward for a length of time or throwing punches is very likely to make them either dive forward and shove you left or initiate a cutscene attack. I find the best strategy is to inch forward very slightly and holding your ground carefully. Mecha-Ghidorah will generally back away from you until they're in the corner. Once they're in the corner try to land a punch while their spirit is low, then back up far enough to get an attack before going forward again to be close after the attack. From there you quickly land a punch and repeat, doing your best to keep them in the corner and unable to retaliate. If you can manage this, even with a few mistakes it is faster than going for Super Godzilla and has no risk of losing the city.

Stage 6

Retrace your steps from the previous map and grab the Super Godzilla station. It will only be there if you avoided 50% city damage in Stage 5. (If it's not there you'll need to go start the fight with Bagan and wait at the far left for 3 minutes to become Super Godzilla) From there go south until you find Bagan and fight him.

Bagan

Start the fight by backing all the way up. I recommend an "anything but Tail Shot" strategy. The goal is to always charge your Super Punch just enough to get any attack but Tail Shot. If you watch while charging your fighting spirit goes up in small increments. The timing varies a bit depending on your fighting spirit, but generally I find the sweet spot is to release the punch immediate after the second increment begins rising. The longer you charge, the more likely you are to get stronger attacks. Body Slam is the best DPS on average, so while you might be inclined to push for more spirit it's worse DPS and you're more likely to be interrupted and attacked while trying to charge. Your spirit goes up as the punch moves you forward so keep where Bagan is standing in mind while charging. Bagan has a very high chance to counterattack, so block after every attack until you see him not charging you. He has a chance to charge you multiple times in quick succession, which can break your guard and then initiate an attack while you're stunned. From my experience this is unreactable and unavoidable, and it usually happens at least once per fight. Once he's dead wait for the score screen to finish and your run is complete.