We have Dales and Fell ponies, which are very stong and stocky ponies. Quite a few are broken to harness, as we do pleasure driving. I get one of them to pull some small chain harrows - the sort that go behind a quad. Never tried ploughing, but I know someone who used to do ploughing matches with his pair of Dales, and assumably ploughed at home with them.
I have a very large horse drawn sledge, and with all the snow, and thinking of getting the ponies to pull the hay and haylage out to the fields on it.
My uncles used to have horses on the farm, and even in he 1970's would use them to take manure out to spread on the fields, and do all the haymaking with them - poor horses would have a long working day in the summer.