I have no idea really what is traditional, but I thought I'd add my opinion, if it helps.
Since it's for a softball team, will they be wearing them during the games? If so, I'd put them on a french clip or a pony O so that they stay secure.
I love the style of bow you've posted, but they may be looking for more like a cheer bow in the school colors or even a pony streamer? I'm not sure.