Sports should not be 'for boys' or 'for girls.' Just let people play/do what they want to play/do, as long as they have the right skills and requirements to actually play it well, it's fine to do it. I do not understand the need to put gender roles on things.
Of course they can. If they want to why not. They can do whatever they want just like how girls can play football with or without boys. Boys and girls have the freedom to do whatever they want as long as it legal. Boys and girl have their own right to do cheer football dance or whatever they want to.