Where do her staggers, pressure, and everything else you named, come from? I get the zoning, but I feel lost the entire match. I wanna get better with her. Other than constantly playing and getting bodied, what else can I do to improve?
The staggers come from every touch risking a tornado / rock wall follow-up. Tornado is 100% safe on block due to pushback and rock wall is safe if amplified (though it has a flawless block gap, but that's a mindgame all its own). Every poke, 1, 11, 2, 21, F2, etc. threatens a rock wall or tornado after to shut down any attempts at taking one's turn back. Every single thing Cetrion does becomes a mindgame as to whether her opponent gets to play the game after.
The pressure comes from the fact that rock wall is also VERY plus (+15 IIRC) and tornado, while not near as plus, puts the opponent at the perfect range for Cetrion to choose to poke, stagger again, or back away with her insane backdash. She also has an advancing mid via F2 which is super easy to hit confirm off of the string it leads into so every instance of her appearing to back away results in a mindgame of her backing away to do far rock wall, zone, come back in with pokes / fast highs, come back in to grab, or come back in with the advancing F2. Note that due to rock wall and tornado being plus the way they are, this all continuously loops into itself every time Cetrion confirms a hit. In addition, she can use ground pound cancel on hit or block to enforce additional pressure mindgames.
The safety comes from basically all of her strings being 100% safe and having knockback on them to put you far enough away that her backdash beats any attempts at advancing on her after blocking. In addition, she has the rock wall / tornado options on block to force things to be safe.
The disjointed hitboxes are pretty self explanatory. A lot of her moves have hitboxes that aren't part of her hurtbox in the slightest (rock wall, tornado, boulders, S1, F2, every hit of 212, etc.).
The mobility comes from her having one of the top 2 best back dashes in the game and a pretty damn good forward dash too. Combined with her disjointed hitboxes reaching far, pushback on attacks, and plus frames on hit, she's extremely slippery and near impossible to pin down. Also: teleport that can
be used in the air.
The mixups are a new addition courtesy of customs allowing players to have the ground pound mixed with actually useful abilities. It's a low so it can cause mixups off any overhead string enders she has.
The unbreakable damage is due to the fact that the Geyser is her only lifting combo extender and that's not used in her best combination. As such, hit confirms for combo purposes lead to the tentacle grab which leaves the opponent standing. Her combo damage isn't anything great (~20% for a bar), but it's entirely unbreakable and leads to her above-mentioned plus frames into pressure / stagger fun.
Toss all this together with Boulder, Air Boulder, Laser, Tentacle, Tornado, and Ground Pound zoning insanity and you have a character that I honestly believe rivals Jacqui for #1 spot on the tier list. If not tied for #1, Cetrion is an EXTREMELY close #2.
EDIT: for getting better, I highly advise going to YouTube and watching videos of how Dragon, one of the top best MK players and a Cetrion loyalist, plays her.