Snaffle is correct
for novice classes
Find out what to wear for other showing classes
Find out what to do in the ring
At local level, there are a lot of other classes that you can enter besides the type and breed classes. As well as novelty classes like 'prettiest mare', 'most handsome gelding', 'pony the judge would most like to take home', these are the main categories of class found. Click on the links to find out what kind of horse goes in each of these classes.
The majority of these classes are open to any breed or type, within certain limits. As a rule, you should turn out to your normal breed standard - so if your horse is a registered native, you would turn out for native classes, and so on. If you have a 'native type' who is unregistered or of an unknown descent then turn out as for natives, but pull and plait the pony.
At local level, plaited tails are just as acceptable as pulled tails - this is not the case at larger or County shows.
Part breds are always shown plaited, unless they are being shown as a traditional coloured or a show cob. This applies even if both breeds that make up the horse are shown unplaited - so a New Forest/Welsh cross is still shown trimmed, pulled and plaited. The only exception is at some native breed shows, where they may be shown unplaited. Check the schedule or with the secretary to be sure.
Tack and rider's dress should go with the type of horse. So a finer 'show type' animal will be in a coloured browband and the rider in a blue or black jacket, and a 'non show type' would have plain and workmanlike tack and the rider wear tweed. Look at different colour tweed jackets here.
A snaffle is correct for any novice class, and double reins for open classes. This is less important at local shows, and judges do have different opinions. Some like to see snaffles in open classes, while others don't. The theory is that by the time you are in an open class, your horse should be well trained enough to be in a double bridle, much like the higher levels at dressage. This is flexible - a judge would rather see a horse going well in a pelham in a novice class than out of control in a snaffle. Pelhams are perfectly acceptable in the show ring as well. 3-ring snaffles, gags or martingales are not correct for ridden classes, although they are acceptable in Working Hunter classes.
Best Turned Out classes do need a description of their own though. Jacket colour etc is not so important - navy for a 'show type' animal, and tweed for cobs or native types. What is important is the standard of presentation. Everything needs to be as clean as possible, and then a bit cleaner. Tack and clothes don't need to be brand new, but they must be scrupulously clean and you must be seen to have made an effort.