yes stallions can be broke to ride or to do whatever you want them to do. But because they are still intact, it takes an experienced person to handle/train them. You have to always keep them in check and not let them get away with anything. Also, being the owner of a stallion you are responsible for everything about him. You have to make sure where he is kept, he cannot get out and reproduce with a mare in heat. I would say if you have no plan on breeding him later on, to get him gelded. There are tons of unwanted grade horses out there that we don't need more.
If you don't mind me asking, what makes you want to get a stallion?