Oh My, that snow looks so cold, Brrrrr! Driving candidates, you never know, Some horses I have thought would not go in have and some I think that would didn't. I do like horses/ponies that push more from behind though. I have also found that lines, that have gone in harness have a tendency to. In other words breeding from harness horses/ponies that have gone in harness, you have more of a success rate. My stallion, his daughter and her mother all went in harness. A friend of mine Anne Mills has driven for 20 years and bred welsh and the line she uses, well they have all gone in harness. You just never know, I could not pick a horse and say it would go in harness or not, I just try and narrow odds down.
Your ponies look like they are in a winter wonderland of snow. Very pretty.
But I wish you luck.