I don't actually expect anyone to ever get really stuck on great centipede, it's not that hard of a boss considering what bosses you have to have beaten to reach it. I haven't seen anyone post a good tips or guide post though and I spent a good long while fighting the ng+ version of the boss trying to get the no damage title so I figured I might as well share what I learned. If you want to skip the individual breakdown stuff, strategy will be at the end.
For starters, this boss only has 5 actual attacks as far as I've found, and it has access to all 5 at all times:
Rock spit: sucks in air and spits a rock at you. Blocking it will take a lot of ki, but it can't do another attack fast enough for that to matter a majority of the time, dodge so you can attack afterwards because this attack leaves it open for 2-4 swings worth if you're close by.
Poison spit: literally the same move as rock spit, except it leaves leaves a poison mist cloud. blocking it takes little stamina and as long as you don't get poisoned through your block, blocking it has no downsides. Same as rock spit it's open for attacks after this move.
Paralysis spit: literally replace the word poison in the previous attack with the word paralysis, it's the same move but with paralysis.
Big bite: rears way back and does a big slamming bite forward. If you see it lean back further than any of the spit attacks the just dodge away, this move has very short range and a big windup. It does take quite a bit of ki to block, but you can block it fine as again this thing can't attack fast enough to punish you if it guard breaks you with this or any of the spits.
Walking chomp: it walks forward on the ground chomping continuously. If great centipede is down and not out of ki, it WILL be doing this move. The startup is instant when it finishes lowering to the ground. Great centipede only moves while doing this move, and it always tracks in the straightest line possible towards you. It can pass through its own body during this attack so don't try to hide like that. Fortunately this move takes next to 0 ki to block and it always stops immediately after hitting you once, including blocking it. You can run away from centipede, but this move is faster than you walking and it lasts a really long time, so just block it, you'll take no damage and it'll stop immediately. You can usually get a hit or two in while it's standing up after it stops this attack.
Now that you know the attacks, it's time to talk about this guy's 2 states: with body and without body.
With body is how the boss starts the fight. Each of the glowing rocks (and the final rock) has its own hp, only the first couple non-glowing rocks and the head are the actual boss. All of the glowing rocks will secrete poison in a small area around it after a while (not really sure on this part, it seemed like it happened once, but it's really not an issue).
Without body happens after the transition (which I'll cover in a second), it's just the head and the first couple segments all of which take damage to the actual boss hp bar.
The transition from body to no body is the key to this fight. Killing any of the glowing rocks will stun the boss and leave it on the ground while the glowing rocks scatter and run away. The glowing rocks are entirely harmless in this state, feel free to ignore them. The important thing that happens during all of this is that the final rock in the chain (not just whatever rock is last, specifically the non-glowing rock with the big tail legs) becomes one of those stationary fill the room with poison rocks right where it was when you killed the glowing rock. If you kill that tail rock, it will not break apart the body, but it will prevent the stationary room filling poison rock from spawning. Also it is important to note that killing any of the glowing rocks causes a stun as if the boss was out of ki, this stays true even after you've killed 1 rock and the rest are scurrying away. If you kill another glowing rock as it's running away it will stun the boss again.
The transition from no body to body is pretty simple. When the boss runs out of ki it will be stunned and fall to the ground, when it gets back up it will be chomping immediately but instead of aiming for you it will be running away. Once the boss has left the area it will reappear with a full body from either the ceiling or one of the wall holes. If it appears from the ceiling it will do one of the spit attacks before approaching, otherwise it will be like the beginning of the fight again and it'll be chomping your way.
This boss is pretty simple, you don't even need some kind of cheese strat to make it simple, it just already is simple.
When the fight starts it will be chomping towards you, block the chomp and it will stand up. Now run to the back of the centipede and start attacking the tail rock. Make sure to keep an eye on the boss's head while doing this because it will be shooting its projectiles at you, although only the rock spit will do a bunch of damage. If you notice the boss lower its head to the floor at any point, just stop attacking and start holding block until you block its chomp and it stands up again.
Once you've killed the tail rock, continue the same strategy but now you want to kill any of the glowing rocks. As soon as one of the glowing rocks is dead the boss will break apart and fall to the ground. If you kill a glowing rock before the tail by accident be sure to rush to where the tail was and kill it before it fills the room with poison. The boss takes extra damage if you hit it in the mouth, more when the mouth is glowing, so focus there while it's down. Be careful though, the boss can wake up chomping so be ready to block as soon as it shows signs of waking up.
Now the boss has no extended body, and you are in the phase of the boss you will be spending the most time in. Dodge the projectiles (or block if you won't get poisoned/paralyzed through your block), get a combo in after each successful dodge, block when it tries to chomp at you. If you stay close it will sometimes try the big bite attack, this has a bigger opening than the other attacks and let's you hit the mouth so keep an eye out for the extra wind up it does.
When you exhaust the boss's ki it will fall over like before, so get some more good hits in. The boss will for sure wake up and start chomping so be careful around the mouth. Get some free hits as the boss is running away, then hold block and look around the ceiling. If you see the boss starts coming from the ceiling get ready to dodge one of its projectiles, otherwise just wait for it to chomp its way over to you and repeat from the start since it has a full body again.
Some final notes:
If you need a second to breathe during the fight, climb the ladder. The boss will take the long way around to get to you. There's also an air purifier up the ladder if you couldn't kill the tail rock before the room filled with poison. You can also pseudo cheese the boss up the ladder, it has trouble getting to you around the pillar so you can use the pillar to block projectiles and get free hits on its back end if you're quick. As far as weaknesses go, it takes plenty enough damage without an element, so don't worry about it unless you're really trying to go quick, in which case I would think you already know or have access to the yokai gallery notes on its weaknesses and resistances.