Bentley is a very orange chesnut so all of his things are dark green, dark blue or black to tone down the 'orangeness'...bright colours clash and look a bit nasty on him.
Yes - where possible they have dark green rugs and bandages, green ropes and headcollars. showjumps are all a mix of dark green/purple/white, feed and water containers are all dark green, box is dark green too. I don't go as far as grooming kit though... It's a combination of my boring addiction to dark green and the family's fondness for purple (& pink when kids were small). Oddly not all that expensive to maintain as green or purple seem popular.
I'm not the type that has everything in matching colours but I do try to stick to a scheme.
My first pony was bottle green and red.
Lady started out with red and navy and has ended up with baby blue and bottle green after going through a mint coloured phase (she's chestnut so mint wasn't really a good look).
Fudge (buckskin) started out in purple and black and I still have the odd item even now, however his colours are meant to be baby blue, navy and grey.
Faye had purple and baby blue.
Merlin the new boy is probably going to have a grey headcollar, rope and numnah (as I have lots of spare grey items) and whatever colour rugs, bucket etc Fudge isn't using.
I'd love to be all co-ordinated though as I'm a bit of a neat freak.