Cybertronians, despite being non-organic in origin, do in fact have to shed their bulky outer armor every now and then. Old plates get brittle or otherwise damaged over time, and while rather energon consuming to regrow, sometimes it just has to happen, especially if rust or other nasty stuff has gotten into it. The missing plates regrow in relatively short order and the shedding only occurs after sufficient damage it taken or once every few vorns or so. Sometimes, the plates can even be removed by a medic with a quick visit if they are loose enough. The only problem with this? Everyone experiences something a little different.
Poor Ratchet suffers from what amounts to alien chickenpox. In order to get all his old armor off, he claws at it like there's no tomorrow. He will die before being caught trying to drag himself along the ground or rubbing himself up against various textured surfaces to get old armor off, but it has happened. It still happens when he's pretty sure he's alone. Optimus was there to watch Ratchet roll around on the Archive carpet many times.
Arcee is lucky in that all her old armor tends to drop within a few hours, but without it, she can't regulate her internal temperature very well. To compensate, she practically turns into a space heater as her systems kick into overdrive. The kids can't touch her without getting burned and the team are left yelping whenever she touches them when they aren't prepared for it.
Bulkhead is forced to endure losing his plates agonizingly slowly. He'll lose a plate, a new one will grow in. He's in a near never ending state of shedding. And so, much to Miko's horror, he'll just lose pieces sometimes. He's not all that concerned since the shedding, while continuous, is so slow. But the humans? It still startles them to hear an ominous THUNK out of nowhere and see a chunk of metal on the ground.
Ultra Magnus, much to his chagrin, turns into a beacon every time he sheds. His already vibrant colors come in even brighter as new armor grows into place. And so for a few weeks, he looks like an exotic fruit of neon blue, bright red, and blinding silver. Sunglasses are required.
Wheeljack likes to say he never sheds, but when he does, he recharges like the DEAD. Growing in new armor is very biologically taxing, and rather than suffering from other side effects, Wheeljack just takes a really long nap. He'll recharge for days at a time, getting up only to raid the fridge and then pass back out again until his armor is back where it should be. The humans have no clue he sheds armor because of this. But Bulkhead knows. He's been the one paying for Wheeljack's shed time groceries since before the war.
Smokescreen has only shed a handful of times, and all those times he was usually instructed to keep out of the way since he was in danger of being skewered without his armor. So now, whenever he sheds, despite experiencing no negative side effects, he instinctually goes to hide somewhere dark and safe until his armor grows back in. This has led to several incidents of someone screaming like a little girl as a spindly Smokescreen capitalizes on his status to scare people whenever they turn on the lights.
Bumblebee doesn't necessarily suffer whenever he sheds old armor, but he's just uncomfortable to look at. The scout tends to look like a plucked chicken whenever he loses his armor, and due to the weight shift when he losses so much mass, he hunches over oddly. In total, he looks a bit ghoulish and it actually hurts the team to witness, so usually he's given a few days off to get himself in order.
Optimus is in a similar boat to Ultra Magnus and Bumblebee on the rare occasion he sheds old armor. He always gives Ratchet a scare by going entirely grey about a week before the shed actually begins. He loses any and all color in affected areas and then proceeds to lose exactly all his armor within a few hours. Then he's left looking like a gangly half grown youngling due to the length of his arms and legs compared to the rest of his body. Megatron never ceases to mock him whenever it happens, but when Optimus's armor comes back in, his shoulders always come in bigger and sharper than before, a fact Megatron despises.
