You need to do something with his tail, it should be switched (left in a v-shape at the bottom) but it's already short so you'll have to be careful not to take too much off. It just looks more natural, they shouldn't have banged tails.
Another good thing would be to pull the straggly hairs out of his mane, just looks neater, but still natural.
He can't be shown with the bit guards or that numnah, if you want to use a numnah it needs to be close fitting to the saddle. The stirrup leathers would be better shortened so they don't stick out past the saddle flap, or left hanging rather than through the keepers. Being black there's quite a bit of a contrast with his coat and they do draw the eye. If you don't ever use a martingale, taking the keepers off the reins will look better.
A single plait (left long) behind the poll will show his head off, and make a convenient bridlepath.
Not sure who's riding, but in some of the photos they look to be pulling on his mouth slightly, which is moving the bit further back and making the bridle seem bigger and making him pin his ears back.
In the ring, unless there are any problems (like steering or mad cantering), let him go, and focus on keeping him going rather than worrying about looking pretty in an outline, which is an easy trap to fall into. It can also feel like you're cantering around the ring for an eternity, so it is easier to let the horse go at their own pace rather than trying to hold them together.
She needs to practise her individual show so it's completely memorised, but needs to be able to adapt it to the ring. It helps to watch the class before, just incase you have to do your show first, so you can see how other people make use of the available space/whether the judge is setting shows, and then you're going into the ring prepared.
There are lots of threads in here about turnout and shows for welsh D's, so those are worth reading.
Have fun, and bring back plenty of photos.
