Transformer clothing

One way that non-Transformer species seem to have influenced Cybertronian culture is the relatively rare occurrence of Transformers wearing clothing.

Capes
From time to time, some high ranked Cybertronians tend to wear capes. Presumably they are a symbol of office, as only generals, commanders, and other such leaders have been seen sporting them. Exactly what material these capes are made from is unknown, but one presumes that Earth-style fabrics are likely extremely rare on Cybertron (which could make the capes even more special, considering).


 * Optimus Prime and Megatron wore capes while serving as the leaders of the Cybertron Alliance. Prime's was purple (the Decepticon color), while Megatron's was red (the Autobot color). Whether this was a symbol of high office, or just a desire to look pretty, is unknown.


 * Alpha Trion has often been shown to be wearing a cape. We don't know why, but he made Optimus Prime and Elita One, so he can wear whatever he wants.


 * Starscream wore a cape, large shoulder pads, and a crown at his coronation as Decepticon leader. The crown alone survived Galvatron's blast (only to be crushed under his feet).


 * The Nine Great Demon Generals mostly wore capes, except Trypticon, who wore a Batman-like cowl in the Zone Story Pages.


 * The members of the Maximal High Council wear capes, too.


 * Armada Scavenger wore a large, body-obscuring cloak when he first arrived on Earth.


 * Great Convoy is a cape. Seriously.


 * Some Transformers have capes that are actually part of their altmode (e.g. Megatron during Beast Machines season 1, Vector Prime in Transformers Cybertron, etc).

Trenchcoats
Quite a few characters have been depicted wearing trenchcoats, mostly when involved in detective work or similarly secretive activity.
 * Nightbeat has been drawn quite a few times wearing a trenchcoat and fedora, due to their connection with detective fiction. He pulls it off pretty well, actually.
 * The Micromaster Air Strike Patrol wore trenchcoats and fedoras while trying to pass as human professional wrestlers. Interestingly enough, these coats somehow obscured large physical protrusions on their bodies (jet intakes, wings, etc.).

Pretenders

 * Most of the Pretender toy had clothing molded onto their Pretender shells. But at this clothing was just for pretend - it's actually part of the Transformer's shell (which itself might be considered a form of clothing).
 * In the TV commercial of Pretenders, human Pretenders can take off and reveal the muscle of the outer shells.
 * In Super-God Masterforce, human Pretenders wear clothes in normal life as well as normal human.
 * Cloudburst also wears a normal clothing in from Marvel Comics continuity.

??????
Sometimes, people on Earth wear clothing to look like various Transformers. Sometimes this is hot, sometimes this is sad.

Others

 * In an early plan to trap the Decepticons, the Autobots had to run around in lab coats. It was very silly.
 * The magic of Christmas once made Optimus Prime dress up in a festive outfit. Obviously the big guy is a little too open to suggestion. Well, Grimlock also did thing like this.
 * Grimlock is a king of fashion, at times wearing a crown, a bandana, an epron, and... err...
 * The Maximal Elders wear robes. They have their reasons, and they do not concern you.
 * The exo-structures of the members of Council of Ancients resemble robes. They also have their reasons.
 * The Jointron brothers have been shown wearing ponchos and sombreros, as well as using mariachi-style guitars and maracas. This is both hilarious and racist.
 * The Space Mini-Con Team and Armada Grindor have disguised themselves as humans using large heavy jackets, coats, baseball caps, hats, sunglasses, and other items of clothing to try to blend in with other people in robot mode.
 * Heinrad wears his God of Time agent's uniform in the end of Beast Wars Neo manga.
 * Six-Speed's curiosity about human clothing led him to examine the closets of his human friends Bud and Coby. However, his attempt to dress like a human basically amounted to putting random articles of clothing on his limbs, looking more ridiculous than clothing-wearing- Transformers normally do. Which is kinda amazing.
 * Bumblebee wore a robe before his wrestling match with Colossus Rhodes.
 * Brawn made a seemingly-metaphorical reference to footwear called proton boots.