Your horse will need to be nicely groomed and plaited (braided). To plait your horse's mane, his mane will have to be pulled. In terms of tack, you should use your usual tack, as long as it is clean and well taken care of. Any restrictions of artificial aids will be stated on your show organizer's website.
You will be able to find instructions on pulling and plaiting on YouTube.
~Deb~
It depends on how formal the show is
I would say yes, many, many people wear cosmetics at horse shows when showing, there are most likely many that may not wear cosmetics, it's a personal choice I would think.
no only wear cream and white jodphurs
If the rider is riding the horse they wear a bridle and a saddle and if they are outside they wear a flymask and / or a fly sheet or nothing and if they're in the stall they will wear nothing or a horse blanket.
horse owners show of tricks EG:jumping.
You can wear casual clothes with a horse riding helmet.
You can wear knee socks without showing your legs by wearing a long skirt.
Horses wear horse shoes on the bottom of their hoofs.
make sure the horse or pony you are riding can do dressage and get a book showing you what to do
a horse costume.
kicks
Horse racing came before horse shows.