ARC Troopers
Advanced Recon Commando troopers were clones with advanced training. Many clone commanders were ARC troopers in leadership positions. The original version was a clone with blue officer markings, a pauldron with blue markings, a kama (or blast skirt) with a blue edge, and a rangefinder. Those with high rank would have the blue replaced with their rank color (ex. red for Captain Fordo) and would get two ammunition pouches for their DC-17 blasters. All ARC troopers are highly independent. This is a legends only variant.
An ARC commander serving under Jedi Master Sev wore the experimental clone armor that was tested by and kept by his group of clones. The only differences in appearance were the upgraded breath filters, the lack of ammunition pouches, and the fact that the yellow stripe on the helmet did not spread to the edges of the visor. This is a legends only variant.
Somewhere between the limited issue of the first and second transitional armors, ARC troopers were used as a testbed for Phase II. A few minor differences from the final variant existed. The audio pickups were different, the fin remained unchanged, and there were no vents on the helmet. ARC troopers now have custom color schemes, a different pauldron, extra boot plates, a more flexible kama, three ammunition pouches (now standard issue), extra chest armor, a unique backpack, a grappling hook, and the indispensable rangefinder.
After Phase II armor was officially released, ARC troopers went from the experimental armor to the standard armor, but it kept the goodies.
ARC gunners are a unique type of ARC gunner that share some features with cold gear clones and the later AT-RT drivers. This is a legends only variant.
Captain Fordo wore a highly unique suit of armor during the Battle of Coruscant that seems to be closely based off of the BARC trooper, which is a speeder bike riding variant of ARC trooper. This is a legends only variant.